Clocks & Sleep doi: 10.3390/clockssleep8020033

Authors: Joud AlBashtawi Hana Zeidan Abdulrahman Al-Tairi Najlaa Al-Marri Mohammed Abdel Hamid Reem Odaiba Shaikha Al-Kurbi Ramez Jaradat Susu M. Zughaier Habib H. Farooqui

Circadian Syndrome (CircS) links metabolic, behavioral, and mental health challenges to disrupted circadian rhythm. Hyperuricemia (HUA) is associated with cardiometabolic disorders; however, its connection to CircS remains incompletely understood. This study aims to determine if HUA can serve as a biomarker for CircS. We analyzed the National Health and Nutrition Examination Survey (NHANES) data (2005–2020) from 27,410 adults. CircS was defined as the presence of at least five out of eight components, encompassing the traditional metabolic syndrome criteria plus three additional factors: short sleep duration, depression, and non-alcoholic fatty liver disease (NAFLD). HUA was set at serum uric acid levels >6 mg/dL (357 µmol/L) for females and >7 mg/dL (416 µmol/L) for males. Multivariable logistic regression identified predictors of CircS, and dose–response relationships were explored. Of 27,410 participants, 2076 (7.57%) had CircS. HUA was found to be the strongest independent predictor of CircS, with an odds ratio (OR) of 3.26 (95% uncertainty interval (UI) 2.80–3.80, p < 0.001). Other important risk factors included chronic kidney disease (CKD) (OR 2.80), female sex (OR 1.44), and smoking (OR 1.29). In addition, older age, lower educational level, and lower income were also linked with higher risk. Higher uric acid levels were consistently linked to metabolic components of CircS more strongly than to depression and short sleep. In conclusion, HUA is linked with a greater risk of CircS. Although testing is simple and widely available, it could be used for early risk detection. Future studies should determine if lowering uric acid improves circadian health.

Clocks & Sleep doi: 10.3390/clockssleep8020032

Authors: Aline Van Stallen Manon De deyne Céline Labie Liesbet De Baets

The rest–activity rhythm (RAR) is a key marker of circadian regulation and is commonly assessed using actigraphy. Emerging evidence suggests that characteristics of RAR, such as amplitude, stability, and regularity, may be associated with pain-related outcomes. However, no systematic review has yet synthesized this evidence across populations and pain conditions. This systematic review aimed to provide an overview of current approaches to measuring and defining RAR and to examine its associations with pain outcomes in both healthy individuals and clinical populations experiencing acute or chronic pain. A systematic search of PubMed, Web of Science, Scopus, and Embase was conducted, with the final search completed on 20 May 2025. Observational studies reporting associations between at least one RAR characteristic and a pain outcome were eligible. Article selection and risk-of-bias assessment using the ROBINS-E tool were performed independently by two reviewers, and findings were synthesized narratively. Seven cross-sectional studies were included, employing diverse analytic methods such as cosinor and non-parametric analyses. Overall, the findings were heterogeneous, suggesting that associations between RAR and pain vary according to the RAR metric used, the analytical approach, and the population studied. Nevertheless, the evidence generally indicates that more robust and well-consolidated circadian rhythms are associated with lower pain, whereas regularity and timing appear to play more context-dependent roles, highlighting the potential relevance of RAR metrics as modifiable targets and the need for standardized measurement approaches.

Clocks & Sleep doi: 10.3390/clockssleep8020031

Authors: Shefali Thanawala Rajat Shah Alphy Lopes Milind Kulkarni Bharat Jain Niranjan Andhalkar

Sleep disturbances and poor sleep quality are growing public health concerns, adversely affecting both physical and mental health. While exogenous melatonin supplements are used to manage the condition, there is limited evidence available on the efficacy of sustained-release (SR) melatonin formulations. This multicenter, randomized, double-blind, placebo-controlled clinical trial evaluated the efficacy and safety of melatonin-SR capsules (2 mg) in healthy adults with poor sleep quality. Participants aged 30–60 years with poor sleep quality received melatonin-SR (2 mg) or a placebo capsule at night for 28 days. Changes from baseline to day 28 in polysomnography (PSG)-derived sleep parameters, Pittsburgh Sleep Quality Index (PSQI), WHO-5 Well-Being Index, sleep diary parameters, and safety profile were evaluated. Of 62 enrolled participants, 59 (melatonin-SR, n = 28; placebo, n = 31) completed the study. Compared with placebo, melatonin-SR supplementation resulted in significant improvements at day 28 in PSG-derived sleep efficiency (change from baseline: 3.49 for melatonin-SR vs. −6.30% for placebo; p = 0.001) and total sleep time (change from baseline: 23.83 for melatonin-SR vs. −39.25 min for placebo; p = 0.001), along with significant reductions in sleep onset latency (change from baseline: −10.28 for melatonin-SR vs. 16.70 min for placebo; p = 0.031) and wake after sleep onset (change from baseline: −14.92 for melatonin-SR vs. 24.71 min for placebo; p = 0.001). Melatonin-SR supplementation demonstrated a large treatment effect for the improvement in sleep efficiency compared with placebo (Cohen’s d = 0.9). A significant reduction in PSQI global scores was observed in the melatonin-SR group from day 07 onwards (change from baseline on day 07: −2.21 vs. −0.23; day 14: −4.86 vs. −0.65; and day 28: −5.61 vs. −0.65 for melatonin-SR and placebo, respectively; p = 0.001). Improvement in subjective psychological well-being was significant from day 14 onwards (change from baseline on day 14: 9.86 vs. 0.77; and day 28: 13.29 vs. 0.77 for melatonin-SR and placebo, respectively; p = 0.001). A significant improvement in subjective sleep parameters at day 28 (p < 0.05) was observed. Reported adverse events in both groups were mild and transient in nature. Supplementation with melatonin-SR 2 mg capsule at night for 28 days was found to be effective and safe in improving objective and subjective sleep quality outcomes and overall well-being in the trial population.

Clocks & Sleep doi: 10.3390/clockssleep8020030

Authors: Emma Visser Niki Antypa Machteld C. Marcelis Claudia J. P. Simons Yvonne A. W. de Kort

Sleep disturbance is a central feature of depression and a proposed pathway through which Bright-Light Therapy (BLT) exerts antidepressant effects. However, little is known about how sleep reorganises day by day during BLT or whether these dynamics relate to symptom improvement. We analysed daily sleep diaries from 66 patients with depression undergoing three weeks of BLT in routine outpatient care. Generalised Additive Mixed Models characterised daily trajectories in sleep timing, continuity, duration, and Subjective Sleep Quality, and weekly changes in sleep regularity were assessed using Root Mean Square of the Successive Differences. Structural Equation Modelling examined whether within-person deviations in sleep parameters mediated changes in depressive symptoms. Sleep timing showed gradual adjustment across treatment, with a progressive 48 min advance in weekday sleep onset. Sleep regularity improved from Week 1 to Week 2 before partially reversing, and the probability of nocturnal awakenings followed a non-linear trajectory. Other sleep parameters showed weaker directional trends. Improvements in Subjective Sleep Quality accounted for a modest portion of the association between treatment progression and reductions in depressive symptoms, whereas changes in sleep timing and regularity were not associated with symptom change. These findings indicate that sleep reorganises gradually during outpatient BLT, with different sleep dimensions evolving on distinct timescales and Subjective Sleep Quality emerging as one observable component linked to symptom improvement. More broadly, the results highlight the value of day-to-day modelling for understanding sleep–mood dynamics during real-world chronotherapy.

Clocks & Sleep doi: 10.3390/clockssleep8020029

Authors: Lin Feng Zhengyan Zhou Yubo Ma Yingying Zhao Hua Wei Xiaochen Zhu

This study investigated the diurnal dynamics of the gut microbiota and core clock gene expression in the red swamp crayfish, Procambarus clarkii. Samples were collected at four time points (06:00, 12:00, 18:00, and 24:00) over a 24 h period. Gut microbiota characteristics were analyzed using 16S rRNA gene sequencing, while quantitative real-time polymerase chain reaction (qPCR) was used to examine the expression patterns of core clock genes, including Cycle (Cyc), Clock (Clk), and cryptochrome type 1 (Cry1), in the hepatopancreas and eyestalk. The results showed that Kruskal–Wallis tests for α-diversity indices (Shannon, Simpson, ACE, Chao1) and PERMANOVA for β-diversity (Bray–Curtis) of the gut microbiota revealed no significant diurnal variation across the four time points (all p > 0.05). Firmicutes, Proteobacteria, and Bacteroidota were the dominant phyla, with norank_o_RsaHf231, ZOR0006, and Bacteroides as the predominant genera. Although the overall microbial structure remained stable, several taxa, including unclassified_c_Bacilli, unclassified_f_Caulobacteraceae, Gemmobacter, unclassified_f_Rhodobacteraceae, Allorhizobium–Neorhizobium–Pararhizobium–Rhizobium, Lactobacillus, and unclassified_f_Vibrionaceae exhibited time-dependent fluctuations. In addition, the relative mRNA expression levels of Cyc, Clk, and Cry1 in the hepatopancreas and eyestalk showed significant diurnal variation. This study reveals the diurnal dynamic characteristics of the gut microbiota and core clock gene expression in P. clarkii, providing a foundation for further investigation of diurnal regulatory mechanisms and physiological adaptations.

Clocks & Sleep doi: 10.3390/clockssleep8020028

Authors: Vincenzo Castiglione Paolo Morfino Iacopo Fabiani Francesco Gentile Edoardo Airò Benedetta Volpi Daniela Cardinale Claudio Passino Alberto Giannoni Michele Emdin

Obstructive sleep apnea (OSA) is a sleep-disordered breathing condition characterized by recurrent upper-airway obstruction, leading to intermittent hypoxemia, sleep fragmentation, and sympathetic activation. OSA is highly prevalent in patients with cardiovascular diseases and is strongly associated with hypertension, atrial fibrillation, coronary artery disease, heart failure, and adverse prognosis. This review summarizes current evidence on the pathophysiology of OSA, its cardiovascular consequences, and available diagnostic and therapeutic strategies, with particular attention to clinical implications in cardiology practice. We discuss established treatments such as lifestyle interventions, continuous positive airway pressure, mandibular advancement devices, and selected surgical options, as well as emerging therapies, including pharmacological approaches targeting weight loss and ventilatory control. While OSA treatment improves symptoms and quality of life, evidence for cardiovascular event reduction remains heterogeneous and appears strongly influenced by patient selection and treatment adherence. Identifying patients most likely to benefit from targeted OSA management remains a key challenge.

Clocks & Sleep doi: 10.3390/clockssleep8020027

Authors: Christine Gharib Catherine Kim Jun Ling Madhu Varma

Obstructive sleep apnea (OSA) is a highly prevalent yet frequently underdiagnosed condition that is associated with significant cardiopulmonary, metabolic, and neurocognitive outcomes. Risk factors for OSA overlap with illnesses commonly observed in intensive care unit (ICU) patients, resulting in a disproportionately elevated burden on healthcare. This structured narrative review synthesizes current evidence regarding the prevalence, diagnostic challenges, and clinical implications of obstructive sleep apnea (OSA) in critically ill adults admitted to intensive care units (ICUs) using PubMed, EMBASE, and Scopus. Key search terms included “obstructive sleep apnea,” “ICU,” and “critical illness.” Results showed that OSA is present in up to 60–70% of ICU patients, yet only ~5% are formally diagnosed during hospitalization. Underdiagnosis is linked to prolonged mechanical ventilation, extubation failure rates as high as 30%, 2-fold higher perioperative complication rates, cardiovascular instability, 1.8-fold greater 30-day ICU readmission rates, and 2.2-fold mortality. Standard screening tools have limited applicability in ICU patients. Emerging alternatives, such as overnight oximetry, polygraphy, and machine learning models lack validation. Our analyses reveal that current diagnostic and treatment strategies are poorly adapted to critically ill patients. Integration of OSA as a part of ICU management, diagnosis, and intervention may reduce readmissions and mortality.

Clocks & Sleep doi: 10.3390/clockssleep8020026

Authors: Lu Liu Wen Zhou Yu Luo Yueyi Zhang Dongxi Wang Ming Chen Zhiming Wang Yan Zeng

Insomnia is common among older adults and is associated with adverse health outcomes, yet evidence on its relationship with healthy lifestyle in Chinese older adults is limited. This study included 4929 participants from the Hubei Memory and Aging Cohort Study (HMACS). A healthy lifestyle score (range 0–6) was constructed based on body weight, drinking alcohol, smoking, regular exercise, diet, and cognitive activity. Participants were categorized into unfavorable (0–2), average (3), and favorable (4–6) lifestyle groups. Insomnia was defined using the Athens Insomnia Scale (AIS ≥ 6), or the Pittsburgh Sleep Quality Index (PSQI > 5). Multivariable logistic regression models were applied to assess the associations of overall and individual healthy behaviors with insomnia risk. Stratified analyses by smoking status and substitution analyses were conducted. Healthier lifestyle was associated with lower risk of insomnia. Compared with the unfavorable group, participants with favorable lifestyle had a 17.5% lower risk of insomnia. Among individual lifestyle behaviors, healthy diet and active cognitive activity were associated with reduced insomnia risk. Stratified analyses showed these associations were only evident among non-current smokers. Substitution analyses suggested that replacing unhealthy behaviors with healthy ones was associated with a lower insomnia risk. Favorable lifestyle, particularly healthy diet and active cognitive activity, is associated with lower insomnia risk among older adults, with stronger associations observed among non-current smokers.

Clocks & Sleep doi: 10.3390/clockssleep8020025

Authors: Kaori Endo Keiichi Shimatani Norimichi Suzuki

While the health benefits of pet ownership are well-documented, research on co-sleeping with pets has yielded conflicting results, often contrasting objective sleep disturbances with subjective satisfaction. This study examined the association between dog or cat co-sleeping and well-being across two age groups: adults and youths. Data were collected through two cross-sectional online surveys involving adults (n = 2675) and youths (n = 1050). Participants reported their pet ownership, co-sleeping status, and well-being using the five-item World Health Organization Well-being Index (WHO-5). Analysis of covariance (ANCOVA) was used to compare WHO-5 scores among three groups: non-owners, owners who do not co-sleep, and co-sleepers. In adults, dog co-sleepers exhibited significantly higher well-being scores compared to non-owners (p = 0.025). However, no significant associations were observed in the youth sample. These findings suggest that while pet co-sleeping is often perceived as disruptive, it may be positively associated with subjective well-being in adult populations. Further longitudinal research is needed to clarify the causal relationship and the specific mechanisms underlying this “pet effect” in the context of shared sleep environments.

Clocks & Sleep doi: 10.3390/clockssleep8020024

Authors: Michalina Rzepka Aleksandra Buczek Tomasz Chmiela Weronika Galus Joanna Siuda Ewa Krzystanek

Sleep disturbances are common in multiple sclerosis (MS) and contribute to increased symptom burden. Behavioral sleep hygiene practices are potentially modifiable factors influencing sleep and related symptoms, yet their role in MS remains insufficiently explored. This cross-sectional study comprised 175 MS patients. Sleep hygiene was assessed using a behavioral checklist covering a regular sleep schedule, avoidance of daytime naps, limitation of evening caffeine intake, reduced evening screen exposure, and optimization of the sleep environment. The instruments included the Fatigue Severity Scale (FSS), the Modified Fatigue Impact Scale (MFIS), the Athens Insomnia Scale (AIS), the Epworth Sleepiness Scale (ESS), and the Hospital Anxiety and Depression Scale (HADS). Higher sleep hygiene adherence was associated with lower daytime sleepiness (ESS: r = −0.18, p = 0.020), anxiety (HADS-A: r = −0.16, p = 0.034), and depression (HADS-D: r = −0.15, p = 0.047). Patients with higher adherence (score ≥ 3) demonstrated significantly lower MFIS, AIS, ESS, and HADS-D scores compared with those with lower adherence (all p < 0.05). Multivariate regression showed that sleep hygiene adherence was independently associated with lower MFIS (β = −3.24, 95% CI: −6.06 to −0.41, p = 0.025), ESS (β = −0.85, 95% CI: −6.06 to −0.41, p = 0.016), HADS-A (β = −0.67, 95% CI: −1.23 to −0.11, p = 0.019), and HADS-D scores (β = −0.62, 95% CI: −1.17; −0.08, p = 0.026). Better adherence to sleep hygiene practices may be associated with a lower symptom burden in MS.

Clocks & Sleep doi: 10.3390/clockssleep8020023

Authors: Prajoona Valsalan Mohammad Maroof Siddiqui

Sleep disorders, such as insomnia, obstructive sleep apnea (OSA), narcolepsy, REM sleep behavior disorder, and circadian rhythm disturbances, represent a rapidly expanding global health burden that is strongly associated with cardiovascular, metabolic, neurological, and psychiatric diseases. Advancements in wearable sensing technologies and Internet of Medical Things (IoMT) infrastructures have expanded the possibilities for continuous, home-based sleep assessment beyond conventional polysomnography laboratories. These Sleep Health Internet of Things (S-HIoT) systems combine multimodal physiological sensing (EEG, ECG, SpO2, respiratory effort and actigraphy) with wireless communication and cloud-based analytics for automated sleep-stage classification and disorder detection. Nonetheless, the digitization of sleep medicine brings about significant cybersecurity concerns. The constant transmission of sensitive biomedical information makes S-HIoT networks open to anomalous traffic flows, signal manipulation, replay attacks, spoofing, and data integrity violation. Existing studies mostly focus on analyzing physiological signals and network intrusion detection independently, resulting in a systemic vulnerability of cyber–physical sleep monitoring ecosystems. With the aim of addressing this empirical deficiency, this review integrates emerging advances (2022–2026) in the AI-assisted categorization of sleep phases and IoMT anomaly detector designs on the finer analysis of CNN, LSTM/BiLSTM, Transformer-based systems, and a component part of federated schemes and the lightweight, edge-deployable intruder assessor models available. The aim of this study is to uncover a gap in the literature: integrated architectures to trade off audiences of faithfulness of physiological modeling with communication-layer security. To counter it, we present a single framework to include CNN-based spatial feature extraction, Bidirectional Long Short-Term Memory (BiLSTM)-based temporal models and Random Forest-based ensemble classification using a dual task-learning approach. We propose a multi-objective optimization framework to jointly optimize the performance of sleep-stage prediction and that of network anomaly detection. Performance on publicly available datasets (Sleep-EDF and CICIoMT2024) confirms that hybrid integration can be tailored to achieve high accuracy [99.8% sleep staging; 98.6% anomaly detection] whilst being characterized by low inference latency (<45 ms), which is promising for feasibility in real-time deployment in view of targeting edge devices. This work presents a comprehensive framework for developing secure, intelligent, and clinically robust digital sleep health ecosystems by bridging chronobiological signal modeling with cybersecurity mechanisms. Furthermore, it highlights future research directions, including explainable AI, federated secure learning, adversarial robustness, and energy-aware edge optimization.

Clocks & Sleep doi: 10.3390/clockssleep8020022

Authors: Hulya Merie Bashair M. Mussa Salah Abusnana

It is noteworthy that disturbances in circadian rhythms and irregular sleep patterns can exert influence over the onset of Type 2 Diabetes (T2DM). Similarly, they can impact the development of Type 1 Diabetes (T1DM). In recent decades, there has been a notable trend towards both reduced and extended sleep durations, with a concurrent rise in occurrences of compromised sleep quality attributable to sleep fragmentation. These sleep disturbances, along with clinically recognized sleep disorders such as sleep apnea and insomnia, have been increasingly associated with a range of detrimental health outcomes. Of particular concern is the growing evidence linking sleep dysregulation to an augmented risk of metabolic diseases, including diabetes. In addition to sleep duration and quality, emerging research suggests that an individual’s chronotype, reflecting their preferred time for going to sleep, may also exert an influence on disease development, particularly T2DM. The habit of going to bed late when compared to the tendency of going to bed early tends to cause significant disruptions to daily social engagements. Eventually, this misalignment may lead to discrepancies in sleep schedules between weekdays and weekends, commonly referred to as social jetlag. The current review aims to discuss the complex relationship between circadian rhythm misalignment, triggered by improper sleep habits such as short or long sleep duration, disrupted chronotype, social jetlag, and sleep disorders, on the subsequent impact on the development of diabetes. Overall, current evidence suggests that circadian rhythm disruption and sleep disorders contribute significantly to metabolic dysregulation and diabetes risk, highlighting the importance of sleep health in prevention and management of diabetes.

Clocks & Sleep doi: 10.3390/clockssleep8020021

Authors: Franco Tavella Michael Gradisar Renske Lok Olivia Walch

Understanding the effects of light on the body at different times of the 24 h solar day is a topic of increasing interest. In this paper, we use a mathematical model from the literature to simulate what would be expected of the human circadian clock on different light schedules. We first reproduce an influential experiment which found eBooks, when compared to a paper book, delayed sleep by roughly 10 min and melatonin onset by 1.5 h. The model is able to match the delay in sleep onset but struggles to reproduce the melatonin phase delay. However, certain initial conditions and parameters are capable of phase shifts consistent with the original study’s magnitude, suggesting that the original study’s finding may have been influenced by the pre-study entrainment or variability among the participants. We next simulate the same protocol under higher daytime light levels (increasing baseline illumination from 90 to 500 lux) and find that brighter daytime exposure reduces both sleep onset latency and the variability in phase delay attributable to evening eBook light. Finally, we explore how the timing of a bright light pulse during the day changes outcomes, such as sleep onset and circadian amplitude, and how these effects interact with light during the other hours of the 24 h day. Together, these modeling results suggest robust daytime light exposure confers resilience against the circadian-disruptive effects of evening light, generating testable predictions regarding the timing and intensity of beneficial light interventions for maintaining circadian alignment.

Clocks & Sleep doi: 10.3390/clockssleep8020020

Authors: José Costa Dias Philippe Peigneux

Brief post-learning wakeful resting periods and local sleep mechanisms have been proposed to support offline memory consolidation processes. Mind-wandering (MW), thought to reflect the occurrence or need for local sleep, has been linked to momentary attentional disengagement and may index transitions toward offline processing states. We hypothesized that resting opportunities administered immediately after probe-caught MW episodes reflecting local sleep need may selectively enhance memory consolidation. In a first experiment, participants learned five blocks of eight paired-associate words; a MW thought probe was administered after each block. In the MW condition, participants were allowed a 3 min quiet, offline pause after the block if they reported MW. In the control condition, no pause was administered. Consolidation was better in the MW than the control condition, supporting the hypothesis. However, Experiment 2 tested the MW-related pause effect by comparing the MW condition to a condition in which pauses were allowed irrespective of MW. Results showed that performance equally improved in both conditions, suggesting that post-learning pause effects would not be MW-specific. However, additional analyses evidenced a positive relationship between MW intensity and memory consolidation in both experiments. Our findings suggest that transient interruption of input during a declarative learning session may favor memory consolidation at wake, partially independently of the attentional state.

Clocks & Sleep doi: 10.3390/clockssleep8020019

Authors: Emilly Francianne Lamego da Silva Guilherme Martins Francimara Diniz Ribeiro Leonardo Martins Guimaraes Rossi Milena Fernandes de Oliveira Camila Fernanda Cunha Brandão Lucas Rios Drummond Lucas Tulio Lacerda Thais de Fatima Bittencourt Oliveira Michael Jackson Oliveira de Andrade

Light exposure is a primary zeitgeber for the human circadian system and plays a key role in shaping sleep–wake patterns during adolescence, a period marked by biological sensitivity and social constraints. How the temporal organization and spectral composition of daily light exposure differ between weekdays and weekends remains poorly understood. Eighteen adolescents (15–17 years) were monitored for seven days using wrist actigraphy with integrated light sensors. Sleep parameters, nonparametric circadian rhythm indices, and time-resolved profiles of ambient and spectral (blue, green, and red) light exposure were analyzed. Repeated-measures ANOVA tested the effects of time of day and day type. Total sleep time and time in bed were longer on weekdays than on weekends (p < 0.05), while sleep latency and WASO did not differ. Circadian indices indicated preserved rhythmic organization. Light exposure showed a robust diurnal profile, with higher spectral irradiance on weekends (p < 0.001), especially in the morning and early afternoon. Significant time × day-type interactions were observed across all spectral bands (p < 0.001), indicating systematic reshaping of daily light profiles. Adolescents exhibit weekday–weekend differences in the temporal and spectral organization of light exposure, affecting the amplitude and shape of overall daily profiles.

Clocks & Sleep doi: 10.3390/clockssleep8020018

Authors: Tony J. Cunningham Shengzi Zeng Seo Ho Song

Major social, cultural, and sociopolitical events routinely disrupt daily life, yet their effects on sleep are rarely conceptualized at the population level beyond anecdotal sharing. The purpose of this Opinion piece is to initiate a preliminary discussion of “public sleep” as a novel construct describing systematic, event-related changes in sleep timing, duration, and quality that emerge coherently within communities in response to shared social experiences. Drawing on similarities with the well-established concept of public mood, we posit that sleep can be shaped by social environments in which shared attention, emotional climate, and coordinated schedules exert systematic influence. In support of this claim, we describe preliminary evidence from diverse domains demonstrating population-level sleep disruption following major events, including the transition to Daylight Saving Time, national elections, prolonged crises such as the COVID-19 pandemic and armed conflicts, and highly salient cultural activities such as major sporting events. These reports from disparate fields provide an initial indication that public sleep disruptions can be acute or prolonged, geographically localized or global, and may be shaped by the duration, emotional intensity, and perceived importance of the associated event. We further highlight the potential public health, safety, social, and economic consequences of collective sleep loss, underscoring its relevance beyond individual well-being. Finally, we outline key directions for future research, emphasizing the need for systematic reviews, mechanistic studies, longitudinal designs, and policy-relevant recommendations. Recognizing public sleep as a measurable population phenomenon would provide a foundation for anticipating, monitoring, and mitigating sleep disruption during periods of collective strain, with implications for both individual health and societal resilience.

Clocks & Sleep doi: 10.3390/clockssleep8020017

Authors: Ana Patrícia Dias Fernanda Loureiro

Sleep is critical for physical growth and healthy child development. Traditionally, interventions targeting sleep improvement in children have focused on the parents. This scoping review aimed to identify and summarize the available evidence on child-focused interventions designed to promote healthy sleep habits among children aged 3–12 in healthcare settings. The review was conducted in accordance with JBI guidelines. A comprehensive search strategy was employed, encompassing databases such as PubMed, CINAHL, Psychology & Behavioral Sciences Collection, Education Source, Scopus, Web of Science, the Public Health Database, and Portugal’s Open Access Scientific Repository. Following identification and screening, 15 articles were included. Three types of interventions were identified: isolated, combined, and structured programs. Overall, the studies suggest that, while sleep-related knowledge tends to improve, achieving sustained, long-term behavioral change remains challenging in this age group. Active child participation appears essential for promoting lasting results and developing more tailored, child-friendly interventions.

Clocks & Sleep doi: 10.3390/clockssleep8020016

Authors: Piphat Kovitkanit Thavatchai Kamoltham

Insomnia is increasingly recognized as a manifestation of multisystem dysregulation characterized by sustained physiological hyperarousal. This review situates insomnia within a framework of reciprocal disturbances across neuroendocrine, inflammatory, and autonomic pathways. It examines the potential roles of cannabidiol (CBD), polyunsaturated fatty acids (PUFAs) derived from hemp seed oil (HSO), and lignans from black sesame oil (BSO) as modulators of upstream biological processes relevant to sleep regulation. Rather than acting as direct hypnotics, these compounds are considered for their capacity to influence convergent mechanisms involved in sleep–wake stability. Preclinical evidence suggests that CBD modulates endocannabinoid and serotonergic signaling, potentially contributing to the regulation of physiological processes associated with hyperarousal. Concurrently, HSO-derived fatty acids support mitochondrial function and lipid-mediated resolution. Sesame lignans further contribute through antioxidant properties linked to redox balance, neurometabolic stability, and modulation of neural excitability. However, the current evidence base is predominantly preclinical, and definitive conclusions regarding therapeutic efficacy or optimal dosing in humans remain limited. Future research should prioritize integrative clinical studies that link these specific biological modulations to standardized sleep outcomes to determine their real-world applicability. Nevertheless, the pathways discussed align with biological domains consistently implicated in established insomnia phenotypes. This review integrates these compounds within a shared hyperarousal framework to highlight convergent upstream mechanisms that extend beyond their individual effects.

Clocks & Sleep doi: 10.3390/clockssleep8020015

Authors: Navya Movva Jaising Salve Kalpana Wankhede Vaishali Thakare Deepak Langade

Ashwagandha, a revered herb in Ayurvedic medicine for over 3000 years, is recognized for its potential benefits in regulating sleep and supporting overall vitality. This study evaluated the comparative effects of Ashwagandha root extract (ARE) and melatonin (MLT) on sleep quality in adults. In this prospective, randomized, double-blind, placebo-controlled trial, 200 men and women aged 18–50 years were randomized to receive ARE (300 mg twice daily; n = 50), MLT (3 mg/day; n = 50), a combination of ARE (600 mg/day) and MLT (3 mg/day; n = 50), or placebo (n = 50) for eight weeks. The primary outcome was the change in sleep onset latency (SOL) from baseline to week eight, measured by actigraphy. Secondary outcomes included actigraphy-based changes in total sleep time (TST), wake after sleep onset (WASO), and sleep efficiency (SE), as well as subjective measures such as the Pittsburgh Sleep Quality Index (PSQI) and the Hamilton Anxiety Scale (HAM-A). At week eight, SOL was significantly reduced across treatment groups, with the ARE–MLT (p < 0.0001) combination showing the greatest improvement. The combination group also demonstrated significant improvements in TST (p < 0.0001), WASO (p < 0.0001), and SE (p < 0.0001), whereas ARE and MLT monotherapy produced moderate but comparable benefits. Inferential analyses confirmed statistically significant improvements in objective and subjective sleep measures (p < 0.0001). Safety analyses indicated that mild adverse events occurred across all groups, with no clinically significant between-group differences. Overall, both Ashwagandha and melatonin improved sleep disturbances in adults, with combination therapy producing the most consistent and pronounced benefits.

Clocks & Sleep doi: 10.3390/clockssleep8010014

Authors: Andrey R. Alexandrov Anton R. Kiselev Mikhail V. Agaltsov Anastasia R. Alexandrova Ivan A. Kudashov

The role of body position during sleep, particularly the supine position, is now recognized as an important factor in the development of sleep-disordered breathing such as snoring, apnea, and hypopnea. This pilot study aimed to evaluate the efficacy of a new wearable vibrotactile device (SoftSleep) in reducing sleep time in the supine position without negatively affecting total sleep duration or perceived sleep quality. This pilot study included 20 healthy volunteers. Sleep was monitored over two consecutive nights: the first night without positional therapy (PT) and the second night using a PT device. The primary outcome measures were total sleep time, sleep duration in the supine position, number of position changes, and subjective sleep quality (using the modified Pittsburgh Sleep Quality Index). Use of SoftSleep showed a significant reduction in the mean proportion of sleep in the supine position from 56.01% to 7.84% (p < 0.001). Total sleep time did not change significantly (7:39 ± 1:33 vs. 7:42 ± 1:19; p > 0.05). A moderate increase in the number of position changes was not accompanied by a deterioration in subjective sleep quality: 90% of participants rated their sleep with the device as very good or fairly good. Only three participants reported brief awakenings, which did not affect their overall perception of nighttime rest. These results indicate that the SoftSleep device effectively promotes sleep in a non-supine position without altering sleep quality or subjective perception of sleep. The high tolerability of the device confirms its potential for further clinical evaluation in patients with positional sleep apnea.

Clocks & Sleep doi: 10.3390/clockssleep8010013

Authors: Mohamed Salem Fawzia Alhor Amr Ouda Soha Halawa Yara Abuazab Ibrahim Elmakaty

Sleep is a fundamental biological process essential for physical, cognitive, and mental health, yet sleep disorders remain underrecognized in primary care. Given the central role of primary care physicians (PCPs) in early identification and management, this study aimed to assess sleep and sleep disorder knowledge among PCPs working within the Primary Health Care Corporation in Qatar. A cross-sectional study was conducted using the validated 30-item Assessment of Sleep Knowledge in Medical Education (ASKME) questionnaire, alongside demographic and clinical practice variables. The primary outcomes were the overall ASKME percentage score and participants achieving adequate sleep knowledge (≥60%). A total of 110 PCPs were included in the analysis. The mean overall ASKME score was 56.5%, and 44.5% of participants achieved adequate sleep knowledge. Knowledge was highest in circadian sleep–wake regulation and basic sleep principles, and lowest in common sleep disorders, sleep architecture, and the effects of drugs and alcohol on sleep. In multivariable logistic regression, years of clinical experience was the only factor independently associated with adequate sleep knowledge. These findings indicate persistent gaps in clinically relevant sleep knowledge among PCPs and underscore the need for targeted sleep education within primary care to support early and effective management of sleep disorders. However, the achieved sample size was substantially smaller than the initially calculated target of 260, limiting statistical power; therefore, the non-significant findings may reflect a Type II error, and the regression analyses should be interpreted with caution.

Clocks & Sleep doi: 10.3390/clockssleep8010012

Authors: Erin E. Kishman Shawn D. Youngstedt Xuewen Wang

Background/Objectives: There are limited data on the dynamic changes in daily composition of movement behaviors (sleep; moderate-to-vigorous physical activity, MVPA; light physical activity, LPA; and sedentary time, SED) and their associations with body weight in postpartum women. The purpose of this study was to examine associations of reallocating time in one behavior to another with body weight, at different times in the first year postpartum. Methods: The study included 86 women who delivered a singleton infant at ≥37 weeks gestation. Physical activity and sleep were measured via actigraphy in early, mid-, and late postpartum. Body weight was measured at each timepoint. Isotemporal substitution models were used to examine the association of reallocating ten minutes of one behavior (MVPA, LPA, SED, or sleep) to another, with body weight. Results: Participants spent most of their day in SED (~52–53%), followed by sleep (~30%), LPA (~12–13%), and then MVPA (~2%) throughout the first year postpartum. In early and mid-postpartum, but not late postpartum, reallocating 10 min of MVPA to LPA, SED, or sleep was associated with lower body weight (range: 3.07–4.03 kg lower). In early and late postpartum, reallocating 10 min of SED to LPA was associated with a lower body weight (4.03 kg and 1.04 kg, respectively). In participants who slept ≥7 h per day, reallocating sleep to LPA in early postpartum, and MVPA time to LPA in mid-postpartum was associated with lower body weight. In those who slept <7 h, no significant associations with body weight were found when reallocating time from one behavior to another. Conclusions: Encouraging LPA throughout the postpartum period may be beneficial for weight loss, and having enough sleep may be especially important for early to mid-postpartum. Future research examining the impact of changes in LPA on body weight in the postpartum period are needed, along with postpartum specific 24 h movement guidelines.

Clocks & Sleep doi: 10.3390/clockssleep8010011

Authors: Miller Martinez Frank Villarreal Lourdes M. DelRosso

Sleep disorders and primary headache syndromes frequently coexist, and accumulating evidence suggests that this relationship is bidirectional and biologically mediated rather than coincidental. Patients with migraine, tension-type headache, and cluster headache commonly report poor sleep quality, insomnia symptoms, and irregular sleep patterns, while individuals with sleep disorders such as insomnia, obstructive sleep apnea, restless legs syndrome, and narcolepsy experience a higher prevalence, severity, and chronification of headache disorders. This narrative review synthesizes current clinical, epidemiologic, and translational evidence supporting shared neurobiological mechanisms linking sleep and headache disorders. We focus on five major overlapping pathways: dopaminergic dysfunction, iron deficiency, hypothalamic and circadian dysregulation, central sensitization, and neuroinflammation. Evidence from population-based studies, clinical cohorts, neuroimaging, genetic research, and experimental models demonstrates that these mechanisms converge within hypothalamic, brainstem, and trigeminovascular circuits that regulate arousal, pain processing, and homeostasis. Conditions such as insomnia, obstructive sleep apnea, restless legs syndrome, and circadian disruption not only exacerbate headache burden but may act as modifiable risk factors that promote headache onset and progression. Recognizing sleep disorders as integral components of headache pathophysiology has important clinical implications, emphasizing the need for systematic sleep assessment and targeted sleep interventions as part of comprehensive headache management strategies.

Clocks & Sleep doi: 10.3390/clockssleep8010010

Authors: Adriana Félix Adelinda Candeias

In the original publication [...]

Clocks & Sleep doi: 10.3390/clockssleep8010009

Authors: Dan-Adrian Epuran Urs Albrecht

The circadian clock enables organisms to anticipate daily recurring events and synchronize their internal rhythms with environmental cues, such as light, aligning with the day/night cycle. Central to the molecular mechanisms of the circadian clock and light sensing are the Period (Per) 1 and 2 genes. While the roles of Per2 in astrocytes and neurons have been characterized, the specific contributions of Per1 remain less understood. Previous research has shown that Per2 in neurons, but not astrocytes, influences phase shifts, whereas the regulation of the circadian period involves Per2 in both cell types. In this study, we investigated the role of Per1 in neurons and astrocytes in modulating the circadian period and phase shifts. Using an Aschoff Type I protocol (constant darkness) combined with 15 min light pulses at circadian times (CT) 10, 14, and 22, we found that the absence of Per1 in neurons—but not in astrocytes—significantly affected both the circadian period and phase advance shifts in response to light at CT22.

Clocks & Sleep doi: 10.3390/clockssleep8010008

Authors: Alen Juginović Laura Rodman

Sleep banking, i.e., preemptively obtaining extra sleep prior to anticipated sleep loss, has been proposed as a strategy to reduce the cognitive and physiological consequences of sleep deprivation. However, our understanding remains incomplete regarding the effectiveness of preemptive sleep extension in enhancing resilience to sleep loss. A comprehensive literature search was conducted using PubMed, MEDLINE, and Embase for studies published between 2004 and 2025. Following a comprehensive literature search, we identified 12 studies meeting the inclusion criteria—seven primary experimental trials comprising approximately 140 participants, predominantly healthy young adults aged 18–39 years. We evaluated the effects of sleep banking on cognitive performance, mood, physiological parameters, and real-world outcomes. Included studies encompassed experimental laboratory trials, observational research, and field studies in occupational and athletic settings. Although the number of studies on sleep banking remains limited, experimental evidence demonstrates that preemptive sleep extension improves objective alertness and vigilance during subsequent sleep restriction or total sleep deprivation. Individuals who obtained additional sleep exhibited fewer attentional lapses, faster reaction times, and improved mood, although subjective sleepiness often remained high. Preliminary field evidence suggests that preemptive sleep extension enhances workplace safety, reduces errors, and improves sustained attention in shift workers. In athletic contexts, sleep banking has been associated with improved physical endurance and reaction speed. Importantly, this review primarily addresses the homeostatic dimension of sleep regulation (Process S); circadian factors (Process C), including chronotype, social jetlag, and circadian timing of sleep extension and testing, were not systematically addressed in the included studies and represent important limitations of the current evidence base. Overall, sleep banking appears to be a viable strategy for enhancing resilience to acute sleep loss. It confers measurable benefits in performance, cognitive function, and physiological markers, supporting its application in high-demand occupations and competitive environments. Although it does not fully eliminate subjective fatigue, sleep banking may serve as a valuable complement to other fatigue mitigation strategies for anticipated short-term sleep loss.

Clocks & Sleep doi: 10.3390/clockssleep8010007

Authors: Carina Fernandes Ema Leite Joana E. Coelho Cátia Reis

Sleep and circadian research in real-life environments is challenging but essential. This study presents the design and implementation of a data-collection protocol in a highly challenging real-life setting over 56 days, examining both researchers’ and participants’ perspectives on its strengths, limitations, and key challenges, and highlighting the lessons learned relevant to future studies in similar contexts. Thirty military submariners completed a questionnaire after the 56-day pre-mission, mission, and post-mission data collection to assess their views on the study and each task. Compliance with measurements (questionnaires, diaries, actigraphy, and blood collections) was quantified and correlated with participants’ answers. Mean global satisfaction was 3.57 ± 0.77 (0–5 scale) and declined across study phases, with a significant change only in the post-mission phase (p < 0.001). Higher work satisfaction correlated with better global study satisfaction (ρ = 0.396; p = 0.030). Diaries were rated the most burdensome task, while blood collections generated the most polarized responses. Compliance with continuous measurements was high, but these also decreased in the third phase of the study, significantly for actigraphy (p < 0.001), although without clear predictors, including satisfaction. In this extreme setting, satisfaction and compliance declined significantly in the final phase of the study, without clear predictive factors. Having different engagement strategies for different work shifts is also an important consideration for future studies.

Clocks & Sleep doi: 10.3390/clockssleep8010006

Authors: Sumin Bae Eunji Hwang Ki-Young Jung

Light exposure profoundly influences human emotions and physiology. Yet, adolescents spend considerable time under artificial indoor lighting. Reduced daytime light exposure delays the circadian clock, negatively affecting sleep, cognition, and mood. This pilot study examined whether 470–490 nm enhanced LED lighting modulates mood, sleep quality, and attention among 65 male Korean high school students (mean age = 15.4 years) who participated in a two-week intervention. Both groups were exposed to natural daylight, but the experimental group additionally used LED lighting enriched in the 470–490 nm wavelength range, whereas the control group used LED lighting without modified spectral characteristics. Students were exposed to the assigned lighting from 08:00 to 17:00 during regular school hours for two consecutive weeks. To evaluate the effects of the two-week intervention, pre- and post-assessments included the Beck Depression Inventory (BDI-II), the Richards–Campbell Sleep Questionnaire (RCSQ), the Epworth Sleepiness Scale (ESS), the Perceived Stress Scale (PSS), and the Frankfurter Attention Inventory (FAIR), administered twice at each assessment point. The linear mixed-effect model showed a significant time × group interaction for line errors in the first FAIR trial (F (1, 52) = 5.21, p = 0.027, η2 partial = 0.09), suggesting a greater relative reduction in attentional errors in the experimental group compared with the control group. No significant effects were observed for sleep- or mood-related outcomes. These results indicate the potential relevance of wavelength-optimized lighting in educational settings where sustained attention is critical. Future studies with larger samples and longer interventions are required to confirm and extend these findings.

Clocks & Sleep doi: 10.3390/clockssleep8010005

Authors: Maria Dalmau i Ribas Geoffroy Solelhac José Haba-Rubio Julien Elowe Véronique Griffith

Insomnia symptoms are very common among psychiatric inpatients and can increase the risk of suicide in this population. However, little is known about how psychiatrists and nurses manage insomnia symptoms in psychiatric inpatients. This study aimed to investigate the views, opinions, and experiences of psychiatrists and nurses regarding inpatients’ sleep complaints in a Swiss psychiatric hospital. This qualitative study used individual semi-structured interviews with a purposive sample of psychiatrists and nurses working in a Swiss psychiatric hospital. Interviews were audio-recorded, transcribed verbatim, and analysed manually using inductive thematic analysis. Ten participants (six psychiatrists and four nurses) were interviewed. Three overarching themes were identified: identifying and classifying sleep complaints, the decision-making process, and the actions taken to respond to the complaint. Insomnia symptoms were approached by psychiatrists and nurses in a highly heterogeneous, non-evidence-based manner, with a lack of adaptation of CBT-I leading to overmedication. This heterogeneity may be explained by the diversity of underlying problems associated with insomnia symptoms, the lack of hospital-specific guidelines, and the fact that current guidelines focus mainly on chronic insomnia and do not fully account for the complexity of psychiatric inpatients.

Clocks & Sleep doi: 10.3390/clockssleep8010004

Authors: Yik Hin Chan Anastasya Maria Kosasih Venetia Kok Yi-Hui Ou Yun Jing Crystal Chng Joshua J. Gooley Chi-Hang Lee

We investigated the effects of Continuous Positive Airway Pressure (CPAP) on blood pressure (BP) and vigilance in taxi drivers with obstructive sleep apnea (OSA). This pilot study recruited taxi drivers aged ≥60 years to undergo polysomnography. Those diagnosed with OSA underwent 6 months of CPAP therapy. Baseline and follow-up assessments included 24 h ambulatory blood pressure monitoring (ABPM) and the psychomotor vigilance test (PVT). Among the 32 participants, 22 (68.8%) were diagnosed with OSA (median age 63.0 [62.0–65.0] years; 21 males). The average CPAP adherence was 3.1 ± 2.3 h per night, with 23.5% using CPAP for more than 4 h per night. There were no significant changes in 24 h mean systolic ABPM (125.9 [116.8–134.9] mmHg to 126.0 [118.3–133.7] mmHg; p = 0.93) or reaction times measured by PVT (2.0 [0.0–3.0] lapses to 2.0 [1.0–3.0] lapses; p = 0.82) after CPAP therapy. A high prevalence of OSA was observed among taxi drivers. CPAP adherence was suboptimal and did not result in significant improvements in BP or vigilance.

Clocks & Sleep doi: 10.3390/clockssleep8010003

Authors: Jolanta Malinowska-Borowska Anna Czupryna Marta Buczkowska Aleksandra Kulik

Background. Exposure to artificial light at night can lead to circadian disruption and health risks. It can cause mood swings, confusion, and depression. The aim of this cross-sectional study was to assess the relationship between the illuminance of urban lighting and the health of residents. Methods: This study was carried out among residents of two similar towns, one with typical street lighting and a Dark Sky Park characterized by reduced lighting. A total of 272 respondents participated in this study. A self-administered questionnaire and the WHOQOL-BREF were used among the respondents. Results. People living in the Dark Sky Park were more likely to be satisfied with their sleep (p < 0.001). In fact, 58.7% of Dark Sky Park residents reported no sleep problems. In the control town, only 49.25% did (p = 0.04). The sleep duration was similar in the two towns, but Dark Sky Park residents were statistically less likely to use sleeping pills and window blinds. People exposed to typical street lighting at night reported suffering from eye diseases, cardiovascular diseases, and mood changes more often than those living in the Dark Sky Park. The environmental and physical quality of life, as measured by the WHOQOL-BREF, were significantly higher in the Dark Sky Park residents than in the control town (p < 0.05). Conclusions. People living in places with limited illuminance declare better health and a higher quality of life in the physical and environmental domains.

Clocks & Sleep doi: 10.3390/clockssleep8010002

Authors: Corrado Garbazza

It is my pleasure to present this collection of abstracts from the 36th Annual Meeting of the Society for Light, Rhythms, and Circadian Health (SLRCH), held in Boston, Massachusetts, at Simmons University and Brigham and Women’s Hospital [...]

Clocks & Sleep doi: 10.3390/clockssleep8010001

Authors: Ronald B. Brown

Late-night feeding, defined in the present review as feeding after 8:00 pm when evening insulin secretion and sensitivity are low, is increasingly prevalent in Western society and is recognized as a disruptor of metabolic homeostasis. Yet health problems related to late-night feeding are largely ignored in time-restricted feeding studies that generally do not extend past an 8:00 pm feeding window. This paper proposes a novel cascade linking late-night hyperglycemia with sleep disturbances and nasal congestion mediated by renal sodium retention, increased plasma osmolarity, and stress hormone release by hypothalamic–pituitary–adrenal axis activation. The narrative describes the circadian decline in insulin sensitivity, which amplifies postprandial glucose surges following late-night feeding. Elevated glucose levels drive renal glucose reabsorption via sodium–glucose cotransporters, promoting sodium retention independent of insulin. Increased sodium retention raises extracellular osmolarity, activating hypothalamic osmoreceptors and stimulating the hypothalamic–pituitary–adrenal axis. Cortisol release promotes alertness, while fluid retention and mucosal edema contribute to nasal congestion and early waking. Supine fluid redistribution during sleep further exacerbates airway narrowing, increasing the risk of sleep fragmentation and obstructive sleep apnea. The present paper fills a gap in current time-restricted feeding literature by integrating renal, osmotic, and neuroendocrine pathways that may be overlooked as underlying mechanisms of dysregulated glucose control and hormone dysfunction. Reviewed evidence suggests that symptoms such as nocturnal congestion and sleep disruption are not merely incidental to late-night feeding but frame late night feeding as a risk factor with underlying physiological stressors that could contribute to cardiometabolic risk.

Clocks & Sleep doi: 10.3390/clockssleep7040070

Authors: Yasunori Oka Akiko Tange Yuki Maeda

This paper reviews existing research on infant mattress design to promote safe and comfortable sleep and proposes evidence-based design recommendations. Focusing on safety related to Sudden Unexpected Infant Death (SUID) and comfort associated with infant development and thermoregulation, we examine mattress firmness, pressure distribution, breathability, and thermal properties. Since infants have difficulty turning over and possess immature thermoregulatory functions, mattress characteristics directly influence sleep quality and safety. Based on international studies, we clarify the requirements for infant mattresses and provide insights into future product development and evaluation standards.

Clocks & Sleep doi: 10.3390/clockssleep7040069

Authors: Ingrid Porto Araújo Leite Viviane Akemi Kakazu Lucca Andrade Teixeira de Carvalho Sergio Tufik Gabriel Natan Pires

Digital Cognitive Behavioral Therapy for Insomnia (dCBT-I) is an effective alternative to therapist-delivered CBT-I. However, there is a lack of meta-analyses assessing its effects on other sleep-related outcomes. We aimed to conduct a meta-analysis of randomized controlled trials (RCTs) evaluating dCBT-I in adults with insomnia through polysomnography (PSG) and sleep diary. Systematic searches were performed in PubMed and Web of Science. The outcomes considered were total sleep time (TST), sleep onset latency (SOL), sleep efficiency (SE), wake after sleep onset (WASO), and number of awakenings (NWAK). Meta-analyses were performed using random-effects models to compare dCBT-I with active (in-person or telehealth CBT-I) or inactive (waiting list, no treatment, or minimal intervention) control groups. Of the fourteen RCTs included, only three employed an active control. As no trials used PSG, the analyses relied solely on sleep diary data. DCBT-I showed no statistically significant differences from active controls, indicating comparable effects with therapist-delivered CBT-I. In contrast, it demonstrated statistically significant effects against inactive controls; TST increased by 0.20 h, SOL decreased by 15.53 min, SE improved by 7.91%, WASO reduced by 15.61 min, and NWAK decreased by 0.53. Future research should prioritize comparisons with therapist-delivered CBT-I and incorporate PSG for measuring these parameters.

Clocks & Sleep doi: 10.3390/clockssleep7040068

Authors: Sandrine Baselgia Jonas Beck Björn Rasch

Anticipation of stressful events can impair sleep quality. In a recent study, we reported that anticipating a stressful task before a nap led to negative changes in sleep parameters, particularly at the end of the nap. In our previous study, we compared stress anticipation with the anticipation of relaxation; thus, the observed effects may have been amplified by sleep quality improvements in the relaxation condition. In the current study, we aimed to replicate these findings using an alternative neutral control condition. The data from a newly collected sample (n = 31) were compared with the data from our previous study (n = 33) using identical analyses. The results reveal an opposite pattern from our previous study: participants in the neutral control condition showed poorer sleep (longer sleep onset latency, reduced slow-wave sleep, and lower SWA/beta ratio) compared to those anticipating stress. In a direct comparison of both studies, sleep parameters in the stress conditions were highly similar across the two studies, suggesting that the divergent outcomes are driven by differences in the control conditions. The temporal dynamic changes observed in our previous study could not be replicated. These findings highlight the importance of carefully considering control conditions in experimental sleep research and suggest that even “neutral” instructions can evoke anticipatory effects. Moreover, the observed benefits of anticipating post-sleep relaxation highlight opportunities for relaxation-based interventions to improve sleep quality.

Clocks & Sleep doi: 10.3390/clockssleep7040067

Authors: Arcady A. Putilov Evgeniy G. Verevkin Dmitry S. Sveshnikov Zarina V. Bakaeva Elena B. Yakunina Olga V. Mankaeva Vladimir I. Torshin Elena A. Trutneva Michael M. Lapkin Zhanna N. Lopatskaya Roman O. Budkevich Elena V. Budkevich Marina P. Dyakovich Olga G. Donskaya Dmitry E. Shumov Natalya V. Ligun Alexandra N. Puchkova Vladimir B. Dorokhov

The circadian phase difference between morning and evening types is a fundamental aspect of chronotype. However, results of categorizations into chronotypes based on reported sleep times show low concordance with those based on measurements of the hormonal or physiological or molecular rhythm–markers of the circadian phase. This might be partially explained by the profound individual differences in the phase angle between the sleep–wake cycle and these rhythms that depends on chronotype, age, sex, and other factors. Here, we examined the possibility of using self-reported sleep times in the condition of 5-days-on/2-days-off school/work schedule to estimate circadian phase differences between various chronotypes. In an in silico study, we determined that, for such an estimation, similarities of the compared chronotypes in weekend sleep duration and weekend–weekday gap and in risetime are required. In the following empirical and simulation studies of sleep times reported by 4940 survey participants, we provided examples of the estimation of circadian differences between chronotypes, and the model-based simulations of sleep times in morning and evening types exemplified a way to confirm such estimations. The results of in silico, empirical, and simulation studies underscore the possibility of using bedtimes and risetimes for direct estimation of the circadian phase differences between individuals in real-life situations, such as a 5-days-on/2-days-off school/work schedule. Additionally, the results of these studies on different chronotypes provided further mathematical modeling and empirical evidence for our failure to sleep more on weekends to recover/compensate/pay back/ catch up on lost sleep.

Clocks & Sleep doi: 10.3390/clockssleep7040066

Authors: Adriana Félix Adelinda Candeias

Sleep is essential for child development, influencing cognition, emotional regulation, behavior, and physical health. Recent studies increasingly frame sleep as both a key developmental process and a modifiable factor shaped by, and shaping environmental risks—including digital screen exposure and psychosocial stress. This systematic review synthesized empirical findings from cross-sectional and cohort studies published between 2019 and 2024 on the associations between sleep duration, quality, and patterns and developmental outcomes in typically developing children aged 6–12 years. Searches were conducted in EBSCO, Scopus, and Web of Science databases, yielding 99 records, of which 20 met inclusion criteria. Methodological quality was evaluated using Joanna Briggs Institute tools. Findings show consistent associations between better sleep and enhanced cognitive performance, emotional well-being, and reduced behavioral problems. Some studies identified sleep as a mediator between screen use and behavioral difficulties, whit additional moderating effects related to gender and socioeconomic status. However, most studies used cross-sectional designs and self-reported measures, limiting causal interpretation. Overall, sleep emerge as a potentially modifiable factor influencing developmental outcomes, based on correlational evidence. Future research should prioritize longitudinal and ecologically valid designs, objective measures, and computational approaches to identify sleep-related risk profiles and guide early interventions.

Clocks & Sleep doi: 10.3390/clockssleep7040065

Authors: Lara Ilona Becker Céline Vetter Karel Kostev Matthias Kalder

Objective: An association between sleep apnea and various urological symptoms has been reported in the literature. Therefore, the aim of this study is to analyze sex-related differences in the association between sleep apnea und subsequent urinary incontinence diagnosis. Methods: This study examined the incidence of urinary incontinence in a matched pair cohort with and without sleep apnea treated in 1293 general practices in Germany between January 2005 and December 2022 (74,453 vs. 372,256 individuals). The five-year cumulative incidence of urinary incontinence in the cohorts with and without sleep apnea was studied using Kaplan–Meier curves and log-rank tests. Finally, a univariable Cox regression analysis was conducted to assess the association between sleep apnea and urinary incontinence. Stratified analyses were conducted by sex (male/female) and age group (18–50 years, 51–60 years, 61–70 years, >70 years). Results: Sleep apnea was significantly associated with urinary incontinence as compared to individuals without sleep disorder diagnosis (5.1% vs. 4.3%; p < 0.001), and this association remained robust in females (HR: 1.38; 95% CI: 1.29–1.46), but not in males (HR: 1.02; 95% CI: 0.96–1.08) In females, the association was strongest in the age group 51–60 years (HR: 1.98; 95% CI: 1.71–2.30). Conclusions: In conclusion, this study reports a significant association between sleep apnea and subsequent urinary incontinence diagnosis. Sex- and age-related differences should be taken into account, as associations were stronger for middle-aged females followed by younger females and no significant association was found regarding males.

Clocks & Sleep doi: 10.3390/clockssleep7040064

Authors: Andrés Camargo Leandro P. Casiraghi Diego A. Golombek Edith Villalobos Viviana González Carlos Orozco Elena Jiménez Danny Sanjuanelo Oscar Pianeta Rafael Vargas

Undergraduate students and healthcare professionals often experience irregular sleep patterns, social jet lag (SJL), and rotating shifts that affect their performance. This study examined the association between SJL, sleep duration, and psychosocial factors among 1409 Colombian undergraduate students (mean age 24.4 ± 6.7 years) using data from the Ultra-Short Version of the Munich ChronoType Questionnaire collected between June and September 2023. Multivariable linear regression analysis identified factors associated with SJL. The prevalence of SJL exceeding two hours was high (84.6%), with an average magnitude of 4.4 h. Chronotype (MSFsc) was negatively correlated with SJL, indicating that students with later chronotypes tended to experience greater misalignment between biological and social time. Younger age and a higher number of working days were significantly associated with increased SJL, whereas substance use and mental health history showed no significant effects. These findings highlight that work-related demands, particularly frequent working days, play a key role in exacerbating social jet lag. The results underscore the need for institutional strategies to promote sleep health among Colombian university students and health professionals.

Clocks & Sleep doi: 10.3390/clockssleep7040063

Authors: Alexandru Ungurianu Virginia Marina

Burnout is increasingly recognized as both a psychosocial and a chronobiological disorder characterized by endocrine dysregulation and circadian disruption. It arises from chronic occupational stress and manifests through psychological, physical, and physiological symptoms. Although psychosocial determinants are well established, the biological and chronobiological mechanisms, particularly those involving cortisol and melatonin, remain less explored. This systematic review synthesizes current evidence on hormonal and circadian dysregulation in burnout and complements it with exploratory observational data from healthcare professionals. Peer-reviewed studies evaluating endocrine or circadian biomarkers in individuals with burnout were systematically reviewed. In addition, an exploratory observational analysis was carried out among 195 Romanian clinicians using an adapted Maslach Burnout Inventory. Morning salivary cortisol was measured once at 9 a.m. in a small subsample (n = 26) to provide preliminary physiological data. Because only a single time point was obtained, these values were interpreted as indicative of stress-related activation rather than circadian rhythm. Thirty-seven studies met the inclusion criteria. Across the literature, burnout was associated with altered HPA-axis activity, blunted diurnal cortisol variation, and irregular melatonin secretion related to shift work and disrupted sleep–wake cycles. Complementary exploratory data from our Romanian cohort indicated strong correlations between burnout severity, physical symptoms, and higher morning cortisol values among shift-working clinicians. These findings are preliminary and not representative of full circadian profiles. Burnout should be considered both a psychosocial and a systemic disorder influenced by endocrine and circadian dysregulation. Recognizing alterations in cortisol and melatonin as objective indicators may facilitate earlier detection and inform chronobiological interventions such as optimized scheduling, light exposure management, or melatonin therapy. The observational data presented here is preliminary and intended to generate hypotheses; future research should employ repeated cortisol sampling under controlled Zeitgeber conditions to confirm circadian associations.

Clocks & Sleep doi: 10.3390/clockssleep7040062

Authors: Sotirios Kakavas Dimitrios Karayiannis

Critically ill patients are predisposed to developing cognitive dysfunction, excessive daytime sleepiness (EDS), and fatigue during their stay in the intensive care unit (ICU). Modafinil, a wakefulness-promoting agent, has demonstrated potential benefits in enhancing alertness, cognitive performance, and activity levels in various clinical populations. The present narrative review aims to systematically evaluate the existing literature regarding the administration of modafinil for the treatment of EDS and fatigue in the ICU context. A comprehensive literature search was performed using the Embase, MEDLINE, Web of Science, and Google Scholar databases, covering publications up to 20 June 2025. Studies investigating the use of modafinil to improve wakefulness in ICU patients were identified. A total of nine relevant studies were included, comprising two randomized controlled trials (RCTs), two case series, and five retrospective cohort studies (n = 950 patients). Four of these studies focused on patients with traumatic brain injury or post-stroke conditions, whereas the remaining studies addressed heterogeneous ICU populations. Preliminary evidence indicates that modafinil may enhance wakefulness in selected critically ill patients and potentially facilitate their participation in rehabilitative interventions, such as physical therapy. Nonetheless, robust conclusions regarding efficacy and safety remain limited by the small sample sizes and methodological constraints of the available studies. Consequently, further large-scale RCTs are warranted to elucidate the therapeutic role of modafinil in the management of EDS and hypoactivity among ICU patients.

Clocks & Sleep doi: 10.3390/clockssleep7040061

Authors: Sara Ahmed Mansoor AlBuhmaid Muneera Jasim Al-Rumaihi Mohammed Adel M Albalawi Ahmed Abdullatif Ahmed Almufarrij Waqar Husain Haitham Jahrami

Circadian rhythm disruptions from shiftwork impact sleep quality and work performance, yet validated tools to assess circadian preferences in Arabic-speaking populations are scarce. This study aimed to translate and validate the 11-item Circadian Type Inventory (CTI-11) into Arabic (CTI-11A), evaluate its psychometric properties, and explore latent circadian profiles in relation to sleep quality. A cross-sectional survey in Bahrain involved 468 Arabic-speaking adults recruited via social media. The CTI-11A, assessing Languid/Vigorous (LV) and Flexible/Rigid (FR) subscales, and the Jenkins Sleep Scale (JSS) were administered. Confirmatory factor analysis (CFA), reliability tests, and latent class analysis (LCA) were conducted. Participants (mean age: 36.18 ± 10.35) showed CTI-11A total scores of 35.40 ± 6.61 and JSS scores of 5.76 ± 3.48. CFA confirmed the two-factor structure (RMSEA = 0.06, SRMR = 0.05, CFI = 0.93, TLI = 0.91), with Cronbach’s α of 0.72 (total CTI-11A). Test–retest reliability was high (ICC = 0.91). CTI-11A correlated moderately with JSS (r = 0.40, p < 0.001), with stronger FR-JSS (r = 0.36) than LV-JSS (r = 0.25) associations. LCA identified two classes (Class 1: 52%, vigorous/flexible; Class 2: 48%, languid/rigid), with Class 2 showing poorer sleep quality. The CTI-11A is a reliable and valid tool for assessing circadian preferences in Arabic-speaking populations, with distinct circadian profiles linked to sleep quality. While flexible/vigorous profiles associated with better sleep, languid/rigid profiles indicate higher sleep disturbance risk, informing targeted shiftwork interventions. Further refinement of the factor structure and broader regional validation are needed.

Clocks & Sleep doi: 10.3390/clockssleep7040060

Authors: Patrícia Andrade Nehme Jefferson Santos Ana Amélia Benedito-Silva José Cipolla-Neto Claudia R. C. Moreno

Background: Shift work necessitates alterations in daily routines, which can be detrimental to workers’ health and may also influence the activity and rest patterns of their children. Aim: The aim of this study was to evaluate the concordance between activity and rest parameters of mothers and their children, according to the mothers’ work shift (day vs. night). Methods: Twelve mother–child dyads participated in this study, including six mothers working night shifts and six working day shifts. All mothers followed a 12/36 h rotating schedule (07:00–19:00 for day shifts; 19:00–07:00 for night shifts). Participants wore actigraphy devices for 10 consecutive days. Sleep and motor activity parameters were analyzed using the Bland–Altman method. Results: Analysis of the five least active hours (L5) revealed increased nocturnal activity among the night shift group. The period of the 10 most active hours (M10) suggested greater activity in the day shift group, with a smaller difference between mother and child in the day shift group. The relative amplitude (RA) in the night shift group was lower among mothers compared to the day group. Interdaily stability (IS) was lower, and intradaily variability (IV) was higher in the night shift group, suggesting more irregular activity patterns. Bedtime data showed greater variability in the night shift group, with night shift mothers typically going to bed later than their children—a pattern that was also observed for wake times. In the day shift group, total sleep time did not differ between mothers and children; however, in the night shift group, discrepancies increased proportionally with total sleep duration. Sleep efficiency was lower among mothers in both groups, but the difference between mother and child was more pronounced in the night shift group. Conclusions: Night shift work among mothers appears to negatively affect both their own and their children’s activity and sleep parameters when compared to those in the day shift group.

Clocks & Sleep doi: 10.3390/clockssleep7040059

Authors: Lourdes M. DelRosso Mamatha Vodapally

Short sleep duration (≤6 h) is a public health concern linked to cardiometabolic disease and premature mortality. However, persistent disparities across sociodemographic, psychosocial, and structural domains remain underexplored in recent nationally representative samples. We analyzed 2022 Behavioral Risk Factor Surveillance System (BRFSS) data, including 228,463 adults (weighted N ≈ 122 million). Sleep duration was dichotomized as short (≤6 h) versus adequate (≥7 h). Complex samples logistic regression estimated associations between sociodemographic, psychosocial, behavioral, and structural determinants and short sleep, accounting for survey design. The weighted prevalence of short sleep was 33.2%. Non-Hispanic Black (AOR = 1.56, 95% CI: 1.46–1.65) and American Indian/Alaska Native adults (AOR = 1.46, 95% CI: 1.29–1.65) were disproportionately affected compared with non-Hispanic White adults. Psychosocial factors contributed strongly: life dissatisfaction, limited emotional support, and low social connectedness increased odds, whereas high connectedness was protective. Food insecurity and smoking were significant structural and behavioral risks, while binge drinking and urbanicity were not. One-third of U.S. adults report short sleep, with marked disparities across demographic, socioeconomic status, psychosocial stressors, and structural barriers. Findings highlight the multifactorial nature of sleep health inequities and the need for multilevel interventions addressing both individual behaviors and upstream determinants.

Clocks & Sleep doi: 10.3390/clockssleep7040058

Authors: Gleb Saharov Barbara Salti Maram Bareya Anat Keren-Politansky Yona Nadir Tamar Shochat

Sleep disturbances and shift work are associated with increased cardiovascular risk, possibly through disruptions in endothelial and hemostatic function. While prior studies link acute sleep deprivation to vascular dysfunction, the impact of chronic sleep quality and circadian misalignment on endothelial health in healthy individuals, particularly shift workers, remains underexplored. The aim of this study was to examine the association between objectively measured sleep quality and endothelial/hemostatic function in healthy female hospital nurses, comparing shift and day workers, and considering time-of-day variation. In this repeated-measures study, 100 female nurses (51 shift, 49 day workers) aged 25–50 wore actigraphy devices for 7–14 days to assess total sleep time (TST), sleep efficiency (SEF), and wake after sleep onset (WASO). Endothelial function was measured using EndoPAT (Reactive Hyperemia Index—RHI). Hemostatic markers included plasminogen activator inhibitor-1 (PAI-1), von Willebrand factor (VWF), heparanase and heparanase procoagulant activity assessed by ELISA, and chromogenic assays in morning and evening. TST was not associated with any vascular outcomes. Poor sleep quality (low SEF, high WASO) was significantly associated with reduced RHI and elevated PAI-1 level, heparanase level, and heparanase procoagulant activity levels. Regression models revealed significant main effects of SEF and WASO on endothelial and coagulation markers, with some interactions depending on shift type and time of measurement. No significant associations were found for VWF. Impaired sleep quality, but not sleep duration, is associated with endothelial dysfunction and procoagulant activation, particularly among shift-working nurses. These findings suggest that sleep quality may play a critical role in vascular health and support the use of sleep-based interventions to reduce cardiovascular risk in shift-working populations.

Clocks & Sleep doi: 10.3390/clockssleep7040057

Authors: Sergey Malykh Valeriia Demareva

Academic performance in adolescence is influenced by both cognitive capacity and physiological factors such as sleepiness. However, the interaction between these dimensions remains understudied. This pilot study examined whether daytime sleepiness moderates the relationship between working memory and academic achievement in a sample of 601 schoolchildren aged 11 to 17 years. Participants completed a digital visuospatial working memory task and self-reported their daytime sleepiness using the Pediatric Daytime Sleepiness Scale (PDSS). Academic performance was assessed through official grades in Mathematics, Language, and Literature. Regression analyses showed that working memory (total score and average reaction time) and daytime sleepiness were independent predictors of academic performance. These findings support our hypotheses that cognitive and physiological factors each contribute to school success. However, no significant moderation effects were found in the full sample. Subgroup analyses revealed that working memory predicted academic outcomes only among students with normal sleepiness levels, whereas in high-sleepiness students, cognitive predictors lost significance and PDSS scores emerged as the dominant predictor. These results suggest that elevated daytime sleepiness can undermine the positive impact of working memory on academic performance. The findings highlight the importance of assessing both cognitive skills and physiological readiness when evaluating students. They also suggest that sleep-focused interventions may improve learning outcomes, especially during adolescence.

Clocks & Sleep doi: 10.3390/clockssleep7040056

Authors: Julia Glueck Celina Pluim McDowell Yakeel T. Quiroz Alice Cronin-Golomb Jeanne F. Duffy

Older adults are vulnerable to changes in sleep with age. Poor sleep quality is associated with self-reported cognitive changes, which can occur before the onset of objective cognitive decline associated with Mild Cognitive Impairment and Alzheimer’s disease. The objective of this study was to examine associations between self-reported sleep complaints, objective sleep quality, and self-reported cognitive changes and their relations to symptoms of depression and anxiety in a group of community-dwelling older adults. Adults aged ≥ 50 without dementia (n = 45) were recruited and completed 1–2 weeks of rest-activity monitoring using a wrist-worn device, underwent a test of global cognitive functioning (Mini-Mental State Examination; MMSE), and completed questionnaires assessing insomnia (Insomnia Severity Index; ISI), subjective sleep quality (Pittsburgh Sleep Quality Index; PSQI), self-reported cognitive changes (Cognitive Function Instrument; CFI), and symptoms of depression and anxiety (Beck Depression Inventory-II; BDI-II and Generalized Anxiety Disorder 7-item assessment; GAD-7). Pearson partial correlations assessed relations among subjective and objective sleep quality, insomnia ratings, CFI ratings, and global cognition, while controlling for BDI-II and GAD-7 ratings. Exploratory analyses examined the correlation between PSQI component scores and CFI ratings and global cognition. Greater ISI (r = 0.50, p ≤ 0.001) ratings significantly correlated with higher CFI scores. PSQI total ratings and actigraphy-based measures (n = 41) did not significantly correlate with CFI scores. Exploratory PSQI subscale analyses revealed that worse subjective sleep quality (r = 0.31, p = 0.048), shorter sleep duration (r = 0.32, p = 0.04), and greater use of sleep medications (r = 0.31, p = 0.048) correlated with higher CFI scores. Poorer sleep quality due to less time spent asleep, fragmented or disturbed sleep, and requiring medications to sleep, may be associated with greater memory concerns. Alternatively, worries about cognition may deleteriously affect sleep. Subjective measures of sleep quality may be useful to identify older adults at increased risk of cognitive decline.

Clocks & Sleep doi: 10.3390/clockssleep7040055

Authors: Shauna Stevenson Haresh Suppiah Toby Mündel Matthew Driller

Ambient temperature and thermoregulation influence sleep quality. This study investigated the effects of a temperature-controlled mattress cover on sleep and perceptual outcomes in healthy adults. In a randomised, counterbalanced, crossover design, 34 healthy adults (20 F, 14 M; age, 30 ± 5 y) used a temperature-controlled mattress cover for 14 nights, following ≥3 nights of familiarisation. The temperature feature was on for 7 nights (POD) and off for 7 nights (CON). Sleep was assessed via wrist actigraphy, while heart rate (HR), heart rate variability (HRV), and respiratory rate (RR) were recorded by embedded sensors in the mattress cover. Participants completed daily and weekly questionnaires evaluating sleep quality, thermal comfort, and thermal sensation. Linear mixed models showed significant main effects of condition favouring POD over CON for all daily perceived outcomes (all p < 0.05). A large, significant improvement in perceived sleep quality was observed (p = 0.001, d = 0.92). No significant differences were found in objective sleep metrics or biometric measures (all p ≥ 0.05). A temperature-controlled mattress cover was associated with improved subjective sleep quality and thermal-related perceptions despite minimal changes in objective or biometric outcomes, which may in part reflect expectancy, or placebo effects. Further research is needed to explore whether these perceptual benefits lead to physiological improvements over time.

Clocks & Sleep doi: 10.3390/clockssleep7040054

Authors: Kaitlyn Chhe Bhavna Kalyanaraman Sophie A. Spielberger Hui-Hsien Lin Stephanie R. Taylor Michelle E. Farkas

The protein SNAIL has been widely studied for its roles in promoting cancer invasion and resistance to apoptosis. There are multiple contributors to its expression, including self- and circadian regulation, and it has been posited that SNAIL oscillates in a circadian manner. Given the multiple factors involved, we sought to determine whether this is indeed the case. We developed a luciferase reporter that was used to demonstrate SNAIL’s rhythmic nature (SNAIL:luc) in the circadian model cell line, U2OS. Considering SNAIL’s relevance in breast cancer, we also assessed its oscillations in cellular models representing different levels of aggression. We incorporated the SNAIL:luc reporter in MCF10A breast epithelial cells, and MCF7 and MDA-MB-231 breast cancer cell lines, which are less and more aggressive, respectively. We found that SNAIL oscillations were present but weak in MCF7 and arrhythmic in MDA-MB-231 cells, correlating with those of core clock genes (BMAL1 and PER2) in these models. Surprisingly, MCF10A cells, whose core clock genes possess robust circadian expression patterns, did not have rhythmic oscillations of SNAIL. Our findings suggest that SNAIL is under circadian control, but this is cell line/tissue dependent, setting the stage for additional studies to better understand the impacts of various factors contributing to its expression.

Clocks & Sleep doi: 10.3390/clockssleep7040053

Authors: Nasrin Mortazavi Puneet Talwar Ekaterina Koshmanova Roya Sharifpour Elise Beckers Ilenia Paparella Fermin Balda Christine Bastin Fabienne Collette Laurent Lamalle Christophe Phillips Mikhail Zubkov Gilles Vandewalle

Animal studies show that sleep regulation depends on subcortical networks, but whether the connectivity between subcortical areas contributes to human sleep variability remains unclear. We investigated whether the effective connectivity between the LC and hypothalamic subparts during wakefulness relates to sleep electrophysiology. Thirty-three younger (~22 y, 27 women) and 18 late middle-aged (~61 y, 14 women) healthy individuals underwent 7-Tesla functional MRI during wakefulness to assess LC–hypothalamus effective connectivity. Additionally, sleep EEG was recorded at night in the lab to examine the relationships between effective connectivity measures and REM sleep theta energy as well as sigma power prior to REM. Connectivity analyses revealed strong mutual positive influences between the LC and both the anterior–superior and posterior hypothalamus, consistent with animal studies. Aging was negatively associated with the connectivity from the anterior–superior hypothalamus (including the preoptic area) to the LC. In late middle-aged adults, but not younger adults, stronger effective connectivity from the anterior–superior hypothalamus to the LC was associated with lower REM theta energy. This association extended to other low-frequency bands during REM and NREM sleep. These findings highlight the age-dependent modulation of LC–hypothalamus interactions and their potential roles in sleep regulation, providing new insights into neural mechanisms underlying age-related sleep changes.

Clocks & Sleep doi: 10.3390/clockssleep7040052

Authors: Ahmed Arabi Humam Emad Rajha Osama Alkeilani Ahmad Hamdan Dima Nasrallah Giridhara R. Babu

Background: Circadian Syndrome (CircS) encompasses a range of cardiometabolic risk factors that contribute to an increased susceptibility to cardiovascular diseases and type 2 diabetes. Understanding the factors that underpin CircS is essential. This study primarily aims to examine the association between hypothyroidism and CircS in adults. A secondary analysis compares this association with that between hypothyroidism and Metabolic Syndrome (MetS). Additionally, the dose–response relationship between serum free thyroxine (FT4) levels and CircS probability is explored. Methods: This cross-sectional study includes 4050 National Health and Nutrition Examination Survey (NHANES) participants (2007–2012). Hypothyroidism was classified into (1) drug-managed, (2) non-drug-managed (NDM) primary, and (3) NDM central hypothyroidism, based on self-reported medication use and serum TSH/FT4 levels. CircS was defined as having ≥5 of its eight components, including MetS criteria, depression, short sleep, and non-alcoholic fatty liver disease. Results: Our results showed that hypothyroidism was significantly associated with CircS (OR: 1.58, 95% CI 1.26–1.98) and MetS (OR: 1.19, 95% CI 1.01–1.42). An inverse, non-linear relationship between serum FT4 levels and the probability of CircS was observed. Conclusions: The results underscore a significant association between hypothyroidism and CircS and MetS, with FT4 levels inversely related to CircS probability. These findings highlight hypothyroidism’s potential role in CircS pathogenesis and prevention.

Clocks & Sleep doi: 10.3390/clockssleep7030051

Authors: Vaida T. R. Verhoef Karin C. H. J. Smolders Geert Peeters Sebastiaan Overeem Yvonne A. W. de Kort

Diagnosis and monitoring of daytime sleepiness remain challenging and are strongly reliant on subjective assessments. To revisit common monitoring tools and explore new assessment modalities, we investigated the response of daily and momentary subjective measures of sleepiness and fatigue and skin temperature to sleep restriction, assessed between- and within-day variations in these responses, and studied their convergence. Seventeen healthy participants (aged 19–32 years, seven females, ten males) participated in a field study employing ecological momentary assessment. After a one-week baseline, two sleep conditions (4 h/night vs. 7–9 h/night, actigraphy-controlled; three nights each) were counterbalanced across participants. During the experimental conditions, sleepiness and fatigue were assessed using subjective rating scales administered in daily diary questionnaires and experience sampling questionnaires (10 notifications per day), while distal and proximal skin temperatures were continuously recorded. Results revealed significant effects of sleep restriction on distal and proximal skin temperature and daily reports of sleepiness and fatigue, independent of the number of sleep-restricted nights. The effects on momentary assessments were moderated by day, reflecting a cumulative effect of the sleep restriction from Days 1 to 3. The effects of sleep restriction on momentary sleepiness and fatigue ratings or hourly skin temperature metrics were not significantly moderated by time of day. Hourly skin temperatures (distal skin temperature and temperature gradient) were significantly related to subjective sleepiness and fatigue. In conclusion, all self-reports were sensitive to the sleep restriction, but momentary assessments illustrate the manipulation’s cumulative effects and captured temporal dynamics in sleepiness and fatigue within days. This investigation showed overlap between sleepiness and fatigue experiences as reflected in medium to strong associations. Skin temperature correlates with momentary subjective sleepiness (and fatigue); however, considering it a proxy for daytime sleepiness remains exploratory.

Clocks & Sleep doi: 10.3390/clockssleep7030050

Authors: Toni Ghayad Anaïs Mungo Matthieu Hein

Attention Deficit Hyperactivity Disorder (ADHD) is a prevalent disorder in the pediatric population. Furthermore, there appears to be a special relationship between ADHD and Restless Legs Syndrome (RLS). The objective of this review was therefore to provide an updated overview of the current literature regarding the prevalence of RLS and its potential clinical impact in pediatric ADHD subjects (<18 years). A systematic literature review was carried out in May 2025 in the PubMed-Medline database according to PRISMA criteria. After evaluation by two readers of the 147 identified articles, 9 articles investigating the prevalence of RLS with or without assessment of its potential clinical impact were selected for this systematic literature review. The prevalence of RLS in children and adolescents with ADHD showed significant variation, ranging from 11% to 54%. One study found a significant impact of RLS on academic performance and life skills in pediatric ADHD subjects. Three studies highlighted higher severity of ADHD complaints in subjects with comorbid RLS. One study reported higher RLS severity scores in the ADHD+RLS group and significantly more severe scores in the “hyperactive-impulsive” ADHD subtype. Two studies identified a significant association between a family history of RLS and RLS+ADHD comorbidity. Compared with the general pediatric population, the prevalence of RLS appears to be higher in pediatric ADHD subjects. Finally, this comorbid sleep disorder could worsen the severity of ADHD symptoms and complicate its clinical management.

Clocks & Sleep doi: 10.3390/clockssleep7030049

Authors: Abdelmajid Lkoul Keltouma Oumbarek Youssef Bouchriti Asmaa Jniene Tarek Dendane

Sleep in intensive care unit (ICU) patients is frequently disrupted, which may adversely affect their overall health and recovery. Despite the implementation of various strategies to promote sleep, accurately assessing its quality remains complex. This pilot study aimed to evaluate both the quality and quantity of sleep in ICU patients using actigraphy (ACT) and the Richards–Campbell Sleep Questionnaire (RCSQ) and to compare the diagnostic performance of these two tools. We conducted a prospective observational study including 228 ICU patients. Sleep was assessed using both RCSQ and ACT. Receiver Operating Characteristic (ROC) curve analysis was used to evaluate the discriminative ability of each tool (Area Under the Curve [AUC], sensitivity, specificity), with optimal cut-off points determined using Youden’s Index. The Mann–Whitney U test was used to compare sleep parameters between patients classified as having good or poor sleep based on ACT measurements. The mean RCSQ score was 38.16 ± 17.09, indicating poor perceived sleep quality. Sleep onset latency (based on RCSQ) was 35.71 ± 21.44 min, with a mean of 40.32 ± 20.03 awakenings. According to ACT, sleep latency was 39.23 ± 22.09 min, and total sleep duration was 198.15 ± 128.42 min (approximately 3 h and 18 min), which is significantly below recommended levels. The average number of awakenings recorded was 24.85. In terms of diagnostic performance, the RCSQ demonstrated excellent discriminative ability (AUC = 1.00 for the total score), while ACT showed more variable results: total sleep duration had a good AUC of 0.91, while sleep latency showed a lower performance with an AUC of 0.50. The RCSQ proved to be more reliable than ACT in assessing sleep quality in ICU patients, providing consistent results across multiple parameters, including sleep depth, latency, and number of awakenings. Conversely, ACT yielded less consistent findings, particularly regarding sleep latency and nighttime interruptions. Further studies are warranted to refine objective tools for evaluating sleep in critically ill patients.

Clocks & Sleep doi: 10.3390/clockssleep7030048

Authors: Sophia Anne Marie B. Villanueva Huei-Bin Wang Kyle Nguyen-Ngo Caihan Tony Chen Gemma Stark Gene D. Block Cristina A. Ghiani Christopher S. Colwell

Individuals with neurodevelopmental disorders (NDDs) often experience sleep disturbances and are frequently exposed to light during nighttime hours. Our previous studies using the Contactin-associated protein-like 2 (Cntnap2) knockout (KO) mouse model of NDDs demonstrated that nighttime light exposure adversely affected behavioral measures. In this study, we exposed wild-type (WT) and Cntnap2 KO mice to an ultradian lighting cycle (T7), which alternates 3.5 h of light and 3.5 h of darkness, hypothesizing that this lighting protocol would mimic the impact of nighttime light exposure seen in standard light–dark cycles with dim light at night (DLaN). However, adult WT and Cntnap2 KO mice held under the T7 cycle did not show the increased grooming behavior or reduced social interaction observed in Cntnap2 KO mice exposed to DLaN. The T7 cycle lengthened the circadian period and weakened the rhythm amplitude without abolishing rhythmicity in either genotype. Finally, opposite to DLaN, neither the T7 cycle nor constant darkness (DD) elicited an increase in cFos expression in the basolateral amygdala. These results demonstrate that the adverse effects of nighttime light exposure in an NDD model depend on the extent of the circadian disruption rather than light exposure alone, emphasizing the importance of circadian stability as a protective factor in NDDs.

Clocks & Sleep doi: 10.3390/clockssleep7030047

Authors: Giulia Belluardo Debora Meneo Silvia Cerolini Chiara Baglioni Paola De Bartolo

The school and university periods represent a critical phase in individuals’ cognitive, emotional, and behavioural development. Numerous lifestyle factors can influence executive functions and high-level cognitive processes crucial for learning and behavioural adaptation. Sleep and physical activity are two variables that influence executive functions and that could be modified through behavioural interventions. Numerous scientific studies suggest that adequate sleep quality and duration are linked to improved cognitive performance. Similarly, regular physical exercise correlates with neurocognitive benefits. However, these two aspects of lifestyle are often compromised in students, resulting in attention difficulties, reduced working memory, and difficulty in inhibitory control, all aspects of non-optimal executive functioning. Even though the scientific literature separately explores “sleep and executive functions” and “physical activity and executive functions”, few studies have integrated the two factors to assess their combined effect on executive functioning, particularly within the student population. The present narrative review aims to outline an integrated theoretical framework of existing scientific literature and to identify any knowledge gaps that may guide future research. It could provide relevant insights for designing preventive or promotional interventions to enhance students’ cognitive performance and mental well-being.

Clocks & Sleep doi: 10.3390/clockssleep7030046

Authors: Suleyman Noordeen Poh Wang Anna E. Strazda Eszter Sara Arany Mehmet Ergisi Linghui Janice Yeo Rebeka Popovic Abinayan Mahendran Mikail Khawaja Kritika Grover Mohammed Memon Saahil Hegde Connor S. Qiu Charles Oulton Yizhou Yu

Concussions significantly impact sleep quality among adolescents. Despite increasing recognition of these effects, the complex relationship between adolescent concussions and sleep disturbances is still not fully understood and presents mixed findings. Here, we conducted a systematic review and meta-analysis to assess how concussions affect sleep-related symptoms in adolescents. We included papers presenting Pittsburgh Sleep Quality Index (PSQI) differences following concussion in high school and collegiate patients, with sleep measures recorded following concussion. Animal studies, research on participants with conditions other than concussion, non-English articles and papers failing to present PSQI data were excluded. We searched MEDLINE®, Embase®, CINAHL, Web of Science™, PsycINFO®, Google Scholar, and Cochrane Central Register of Controlled Trials databases until 23 August 2024. In addition, we performed hand-searching of relevant reference lists and conference proceedings to identify further studies. Risk of bias was assessed using the Newcastle–Ottawa scale. In total, we considered 4477 studies, with nine meeting the inclusion criteria. Our analysis involved 796 participants, 340 of whom had experienced a concussion. Analysis was carried out using the meta and metafor packages in R (version 4.0.0). We showed a deterioration in sleep quality post-concussion, as evidenced by increased PSQI (standardised mean difference 0.84; 95% CI 0.53–1.16; p < 0.0001). Subgroup and quality assessments confirmed the consistency of these findings. Since poor sleep quality impacts daytime activities, we analysed the relationship between concussion and daytime dysfunction. We showed that concussion is associated with a significant worsening of the daytime dysfunction score by 0.55 (95% CI 0.24–0.70; p = 0.006). We conclude that concussions impair both sleep quality and daytime functioning in adolescents. Our research underscores the need for systematic inclusion of sleep quality assessments in post-concussion protocols and calls for targeted interventions to manage sleep disturbances post-concussion to mitigate their broader impacts on daily functioning.

Clocks & Sleep doi: 10.3390/clockssleep7030045

Authors: Anhui Wang Jeroen Vreijling Aldo Jongejan Valentina S. Rumanova Ruth I. Versteeg Andries Kalsbeek Mireille J. Serlie Susanne E. la Fleur Peter H. Bisschop Frank Baas Dirk J. Stenvers

The circadian rhythm of the central brain clock in the suprachiasmatic nucleus (SCN) is synchronized by light. White adipose tissue (WAT) is one of the metabolic endocrine organs containing a molecular clock, and it is synchronized by the SCN. Excess WAT is a risk factor for health issues including type 2 diabetes mellitus (DM2). We hypothesized that bright-light exposure would affect the human WAT transcriptome. Therefore, we analyzed WAT biopsies from two previously performed randomized cross-over trials (trial 1: n = 8 lean, healthy men, and trial 2: n = 8 men with obesity and DM2). From 7:30 h onwards, all the participants were exposed to either bright or dim light. Five hours later, we performed a subcutaneous abdominal WAT biopsy. RNA-sequencing results showed major group differences between men with obesity and DM2 and lean, healthy men as well as a differential effect of bright-light exposure. For example, gene sets encoding proteins involved in oxidative phosphorylation or respiratory chain complexes were down-regulated under bright-light conditions in lean, healthy men but up-regulated in men with obesity and DM2. In addition to evident group differences between men with obesity and DM2 and healthy lean subjects, autonomic or neuroendocrine signals resulting from bright-light exposure also differentially affect the WAT transcriptome.

Clocks & Sleep doi: 10.3390/clockssleep7030044

Authors: Christian J. Wiedermann Verena Barbieri Stefano Lombardo Timon Gärtner Klaus Eisendle Giuliano Piccoliori Adolf Engl Dietmar Ausserhofer

Patient activation enhances self-management of chronic illnesses, and sleep quality is vital for health. The link between activation and sleep quality and the mediating role of chronic diseases remain underexplored. This study examined the association between patient activation and sleep quality, variations across chronic disease groups, and whether chronic diseases mediate this relationship. A population-based cross-sectional survey in South Tyrol (Italy) included 2090 adults (55.0% response rate). Patient activation was measured using the Patient Activation Measure (PAM-10), and sleep quality was measured using the Brief Pittsburgh Sleep Quality Index (B-PSQI). The presence and number of chronic diseases were self-reported. Bivariate analyses, multiple linear regression, and mediation analyses (PROCESS) were performed. Among the participants, 918 (44%) reported at least one chronic disease. These individuals had poorer sleep (B-PSQI mean: 5.05 ± 3.26 vs. 3.66 ± 2.65; p < 0.001) and lower patient activation (PAM-10: 54.4 ± 12.7 vs. 57.2 ± 12.5; p < 0.001) than those without. A negative correlation between PAM-10 and B-PSQI was observed (r = −0.12, p < 0.001), with stronger associations in patients with hypertension and mental illness. In adjusted regressions, chronic disease, female sex, and older age predicted poorer sleep, whereas higher PAM-10 scores predicted better sleep. Mediation analyses showed that chronic disease partially mediated the relationship between patient activation and sleep quality, accounting for 4.7% to 6.3% of the total effect. Conclusions: Higher patient activation correlates with better sleep quality, although this relationship is partly mediated by the chronic disease burden. Sleep disturbances persist across chronic conditions, despite good self-management. These findings highlight the importance of adopting strategies to manage chronic diseases and sleep disturbances, acknowledging that while patient activation is statistically associated with sleep quality, the strength of this relationship is limited.

Clocks & Sleep doi: 10.3390/clockssleep7030043

Authors: Vlad Bucurescu Laure Peter-Derex Maria Livia Fantini Benjamin Putois

Hypersomnia may be classified as primary or secondary, with secondary hypersomnia arising from a variety of underlying causes. Thus, according to ICSD3-TR classification, the diagnosis of idiopathic hypersomnia (IH) is established based on (1) excessive daytime sleepiness (EDS); (2) electrophysiological findings including either a mean sleep latency of less than 8 min on the Multiple Sleep Latency Test (MSLT) or increased total sleep (≥11 h) on 24 h polysomnography; and (3) systematic elimination of other potential etiologies, including sleep deprivation, substances, and medical, psychiatric (notably mood disorders), or sleep disorders. Nevertheless, the clinical heterogeneity observed in IH fuels an ongoing debate, reflecting the limited understanding of its underlying pathophysiological mechanisms. This report describes the case of a patient presenting with a clinical and polysomnographic phenotype of IH (MSLT < 8 min). A comprehensive psychopathological evaluation was performed to explore the possibility of secondary hypersomnia, which revealed features consistent with complex post-traumatic stress disorder (c-PTSD). Psychotherapy focused on c-PTSD was administered with positive and objective results in hypersomnolence/EDS. This clinical improvement suggests a potential relationship between psychological trauma and hypersomnia, a connection that is rarely described in the literature and warrants further investigation. This case highlights the need for a comprehensive assessment of secondary factors, particularly complex trauma, even in the presence of a clinical and polysomnographic phenotype consistent with IH.

Clocks & Sleep doi: 10.3390/clockssleep7030042

Authors: Daniel Zenteno Gerardo Torres-Puebla Camila Sánchez Rocío Gutiérrez María José Elso Pablo E. Brockmann

This study described and analyzed the results of cardiorespiratory polygraphic studies in infants under three months who were hospitalized and monitored due to suspected apneas. Methods: Cross-sectional study. Patients aged <3 months hospitalized from 2011 to 2023 were included. All were referred for suspected apneas, and cardiorespiratory polygraphies (PG) were conducted simultaneous to non-invasive monitoring. Demographic, PG, and diagnostic variables were recorded. PG values were obtained and compared between diagnostic groups. Association was evaluated according to diagnosis, prematurity, presence, and alteration type with Kruskal–Wallis, Wilcoxon, and Fisher tests. Association between quantitative variables was assessed with Spearman’s rho and the presence of alteration with binomial logistic regression. Analysis was performed with Jamovi v.2.3, and statistical significance was defined as p < 0.05. Results: A total of 155 studies were included. Median age was 41.0 days (IQR 22.0–59.0), median gestational age was 38 weeks (IQR 32.0–42.0), and 52.3% were premature. Diagnosis: brief resolved unexplained events (BRUE) (58.1%), apnea of prematurity (27.1%), hypotonic syndrome (7.1%), laryngomalacia (LGM) (3.9%), and craniofacial alterations (CFA) (3.9%). Altered results in 21.9% polygraphies: 44.1% with AHI ≧ 5/h and 20.6% with SpO2 ≦ 90% in >5% of the record. CFA and LGM patients had a higher risk of an altered polygraph than those with apnea of prematurity (OR 21.3/8.5) and BRUE (OR 35.9/14.3), respectively. Conclusions: Infants under three months of age referred for apnea showed often abnormal polygraphic indices, showing significant differences between diagnostic groups. Performance of sleep studies in these groups was feasible and allowed to confirm the presence of apneas and their level of severity. Particular attention should be considered in children with CFA and LMG, since their risk is significantly higher. Age-specific apnea patterns seem to be of interest, as this may possibly lead to future consequences.

Clocks & Sleep doi: 10.3390/clockssleep7030041

Authors: Teruhisa Miike

In humans, the master circadian clock, present in the suprachiasmatic nucleus, plays an important role in controlling life-sustaining functions. The development of the circadian clock begins in the fetal period and is almost completed during infancy to early childhood, based on the developmental program that is influenced by the mother’s daily rhythms and, after birth, with the addition of information from the daily life environment. It is known that circadian rhythms are deeply related not only to the balance of a child’s mental and physical development but also to maintaining mental and physical health throughout one’s life. However, it has been suggested that various health problems in the future at any age may be caused by the occurrence of circadian disturbances transmitted by the mother during the fetal period. This phenomenon can be said to support the so-called DOHaD theory, and the involvement of the mother in the maturation of appropriate and stable circadian rhythms cannot be ignored. We consider the problems and countermeasures during the fetal and infant periods, which are important for the formation of circadian clocks.

Clocks & Sleep doi: 10.3390/clockssleep7030040

Authors: Alyssa Tisdale Nahyun Kim Dawn A. Contreras Elizabeth Williams Robin M. Tucker

This study examined data from participants who completed the SLeep Education for Everyone Program (SLEEP) to explore how various demographic variables affected sleep outcomes and to determine which participant characteristics predicted success. A total of 104 individuals participated. The Sleep Hygiene Index (SHI) measured undesirable sleep behaviors; the Pittsburgh Sleep Quality Index (PSQI) assessed sleep quality and self-reported sleep duration. Participant demographic information was collected at baseline. A mixed ANOVA evaluated group differences, and a multiple linear regression model identified predictors of sleep improvements. Change in SHI scores from pre- to post-intervention demonstrated a significant time × group interaction between Black and white participants (p = 0.024); further analysis indicated Black participants improved more. Better baseline scores predicted more favorable post-intervention outcomes for SHI, PSQI, and sleep duration. Fewer chronic conditions predicted better post-intervention SHI and PSQI scores. Older age also predicted better SHI scores. More favorable initial scores, fewer chronic conditions, and older age were the strongest predictors of positive outcomes following SLEEP. Improved sleep hygiene, sleep quality, and sleep duration were observed over time within subjects across all groups. In summary, SLEEP appears to be effective. Further work exploring challenges experienced by younger participants or those with multiple co-morbidities is warranted.

Clocks & Sleep doi: 10.3390/clockssleep7030039

Authors: Mira Alfikany Khaula Sakhr Stef Kremers Sami El Khatib Tanja Adam Ree Meertens

Short sleep has been linked to overweight, possibly via alterations in appetite-regulating hormones, but findings are inconsistent. Sex differences may contribute to this variability. This systematic review examines whether sex modifies the hormonal response to sleep curtailment. PubMed, Embase, Cochrane, CINAHL, and PsycINFO were searched for English-language experimental studies published before December 2024. Included studies assessed at least one appetite-regulating hormone and presented sex-specific analyses. Studies involving health conditions affecting sleep, circadian misalignment, or additional interventions were excluded. Risk of bias was assessed using the Revised Cochrane Risk-of-Bias tool (RoB 2). Eight studies (n = 302 participants) met inclusion criteria. A narrative synthesis of the findings was conducted for each hormone separately to explore potential differences in their response to sleep restriction. Some sex-related variations in hormonal response to sleep restriction have been observed for leptin (four studies, n = 232), insulin (three studies, n = 56), glucagon-like peptide-1 (one study, n = 27), ghrelin (three studies, n = 87), adiponectin (two studies, n = 71) and thyroxine (two studies, n = 41). However, findings were inconsistent with no clear patterns. No sex-related differences were found for glucagon or PYY, though data were limited. Findings suggest sex may influence hormonal responses to sleep restriction, but inconsistencies highlight the need to consider factors such as BMI and energy balance. Well-controlled, adequately powered studies are needed to clarify these effects.

Clocks & Sleep doi: 10.3390/clockssleep7030038

Authors: Teresa Bernadette Steinbichler Birte Bender Roland Hartl Verena Strasser Daniel Sontheimer Sladjana Buricic Barbara Kofler Birgit Högl Herbert Riechelmann Benedikt Hofauer

Background: Uvulopalatopharyngoplasty (UPPP) and expansion sphincter pharyngoplasty (ESP) are two standard surgical procedures for the treatment of snoring and obstructive sleep apnea. In a retrospective clinical trial, we compared the two surgical techniques regarding objective sleep parameters and patients’ reported outcomes. Materials and Methods: Patients treated with UPPP or ESP between January 2016 and February 2020 were included in this retrospective clinical trial. Pre- and postoperative AHI, BMI, and smoking habits were recorded. Subjective improvement was assessed by the ESS score and symptom relief reported by patients and their bed partners. Results: Between 2016 and 2020, 114 patients were included in the study, 74 patients suffered from OSA, and 30 patients had non-apnoeic snoring (AHI < 5/h). No preoperative sleeping studies were available in 10 patients (10/114; 9%). Based on the findings during drug-induced sedation endoscopy, most patients received an ESP (71/114, 62%), and 43 patients received a UPPP (43/114, 38%). Additionally, in 52/114 (46%), radio frequency ablation of the tongue base was performed if DISE revealed retrolingual collapse. ESP reduced AHI from 21.1 ± 10.8/h to 13.3 ± 12.1/h (p = 0.04), whereas UPPP caused a non-significant decrease in the AHI from 25.0 ± 13.8/h to 18.2 ± 14.6/h (p = 0.6). A minor secondary bleeding was observed in 32 patients, which was effectively treated with electrocautery or conservative therapy (32/114). This was more common in the ESP group (22/71; 31%) than in the UPPP group (10/43; 23%). Postoperative need for analgesics was higher in the ESP group than in the UPPP group. The ESS score showed no significant improvement after UPPP or ESP (p = 0.3), but subjective improvement in snoring was reported by 87/114 (76%) patients. Conclusion: AHI reduction was significantly higher in the ESP patient group than in the UPPP group. ESP patients had a slightly higher rate of minor secondary bleeding and postoperative need for analgesics than UPPP patients.

Clocks & Sleep doi: 10.3390/clockssleep7030037

Authors: Soha A. Hassan Katrin S. Wendrich Urs Albrecht

The circadian clock is a self-sustaining oscillator with a period of approximately 24 h, enabling organisms to anticipate daily recurring events, such as sunrise and sunset. Since the circadian period is not exactly 24 h and the environmental day length varies throughout the year, the clock must be periodically reset to align an organism’s physiology with the natural light/dark cycle. This synchronization, known as entrainment, is primarily regulated by nocturnal light, which can be replicated in laboratory settings using a 15 min light pulse (LP) and by assessing locomotor activity. An LP during the early part of the dark phase delays the onset of locomotor activity, resulting in a phase delay, whereas an LP in the late dark phase advances activity onset, causing a phase advance. The clock gene Period 2 (Per2) plays a key role in this process. To investigate its contributions, we examined the effects of Per2 deletion in neurons versus astrocytes using glia-specific GPer2 (Per2/GfapCre) knockout (KO) and neuronal-specific NPer2KO (Per2/NesCre) mice. All groups were subjected to Aschoff type II protocol, where an LP was applied at ZT14 or ZT22 and the animals were released into constant darkness. As control, no LP was applied. Phase shift, period, amplitude, total activity count, and rhythm instability were assessed. Our findings revealed that mice lacking Per2 in neurons (NPer2) exhibited smaller phase delays and larger phase advances compared to control animals. In contrast, mice with Per2 deletion specifically in glial cells including astrocytes (GPer2) displayed normal clock resetting. Interestingly, the absence of Per2 in either of the cell types resulted in a shorter circadian period compared to control animals. These results suggest that astrocytic Per2 is important for maintaining the circadian period but is not required for phase adaptation to light stimuli.

Clocks & Sleep doi: 10.3390/clockssleep7030036

Authors: Andreea Petra Ungur Andreea-Iulia Socaciu Maria Barsan Armand Gabriel Rajnoveanu Razvan Ionut Carmen Socaciu Lucia Maria Procopciuc

Burnout syndrome is characterized mainly by three criteria (emotional exhaustion, depersonalization, and low personal accomplishment), and further exacerbated by night shift work, with profound implications for individual and societal well-being. The Maslach Burnout Inventory survey applied to 97 medical care professionals (with day and night work) revealed different scores for these criteria. Blood metabolic profiles were obtained by UHPLC-QTOF-ESI+-MS untargeted metabolomics and multivariate statistics using the Metaboanalyst 6.0 platform. The Partial Least Squares Discrimination scores and VIP values, Random Forest graphs, and Heatmaps, based on 99 identified metabolites, were complemented with Biomarker Analysis (AUC ranking) and Pathway Analysis of metabolic networks. The data obtained reflected the biochemical implications of night shift work and correlated with each criterion’s burnout scores. Four main metabolic pathways with important consequences in burnout were affected, namely lipid metabolism, especially steroid hormone synthesis and cortisol, the energetic mitochondrial metabolism involving acylated carnitines, fatty acids, and phospholipids as well polar metabolites’ metabolism, e.g., catecholamines (noradrenaline, acetyl serotonin), and some amino acids (tryptophan, tyrosine, aspartate, arginine, valine, lysine). These metabolic profiles suggest potential strategies for managing burnout levels in healthcare professionals, based on validated criteria, including night shift work management.

Clocks & Sleep doi: 10.3390/clockssleep7030035

Authors: Arcady A. Putilov Evgeniy G. Verevkin Dmitry S. Sveshnikov Zarina V. Bakaeva Elena B. Yakunina Olga V. Mankaeva Vladimir I. Torshin Elena A. Trutneva Michael M. Lapkin Zhanna N. Lopatskaya Roman O. Budkevich Elena V. Budkevich Natalya V. Ligun Alexandra N. Puchkova Vladimir B. Dorokhov

Morningness-eveningness is usually assessed as either a trait or a state using either a morning–evening preference scale or sleep timing reported for free days, respectively. These assessments were implemented in numerous studies exploring the associations between morningness-eveningness and health, mood, and sleep problems. Evening types almost always had more problems than morning types. We examined these associations in university students with conflicting results of trait and state assessments of morningness-eveningness and tried to confirm their chronotype using a multidimensional chronotyping approach that recognizes four types other than morning and evening (lethargic, vigilant, napping, and afternoon). The conflicting trait and state assessments of morningness-eveningness were found in 141 of 1582 students. Multidimensional chronotyping supported morningness of morning types with late weekend sleep timing, and the associations with health, mood, and sleep problems resembled the associations of other morning types (i.e., these associations persisted despite late sleep timing). In contrast, evening types with early weekend sleep timing were more likely classified as lethargic or napping types rather than evening types. They did not resemble evening types in their associations with health, mood, and sleep problems (i.e., early sleep timing did not change these associations). Model-based simulations of the sleep–wake cycles of students with conflicting trait and state assessments suggested that their bedtimes cannot be solely determined by their biological clocks. On weekdays or weekends, mind-bedtime procrastination can lead to missing the bedtime signal from their biological clocks (i.e., self-deprivation of sleep or, in other words, voluntary prolongation of the wake phase of the sleep–wake cycle).

Clocks & Sleep doi: 10.3390/clockssleep7030034

Authors: Yuki Tanaka Yuichiro Otsuka Suguru Nakajima Osamu Itani Tomomi Miyoshi Yoshitaka Kaneita

Worsening adolescent mental health is a significant social issue. Although dreams may reflect one’s mental state, few studies have focused on adolescents. Therefore, this study investigated the relationship between dream content and mental health, specifically anxiety disorder and depressive symptoms, among Japanese adolescents. This cross-sectional study obtained data on gender, grade, age, lifestyle habits, weekday sleep duration, anxiety disorder symptoms, depressive symptoms, and dreams from Japanese high school students. The data were analyzed via multiple logistic regression analyses. The prevalence of anxiety and depressive symptoms increased with the frequency of “rumination at bedtime”, “memory of dreams”, “emotional carryover”, and “awakening by frightening”, “unpleasant”, “film-like”, “fantastical”, and “recurring” dreams. However, this was not the case for “pleasant dreams”. Furthermore, “rumination at bedtime” (anxiety disorder symptoms: adjusted odds ratio: 10.60; 95% confidence interval: 5.92–18.97; depressive symptoms: 8.79, 5.58–13.87) and “unpleasant dreams” (anxiety disorder symptoms: 5.25, 2.86–9.64; depressive symptoms: 10.13, 5.57–18.44) exhibited particularly high odds ratios. “Rumination at bedtime” and “unpleasant dreams” may serve as early indicators of declining mental health. School- and parent-led interventions aimed at improving mental well-being may help prevent the progression or exacerbation of anxiety and depressive symptoms among adolescents.

Clocks & Sleep doi: 10.3390/clockssleep7030033

Authors: Leidivan Sousa da Cunha Beatriz Maria Dias Nogueira Flávia Melo Cunha de Pinho Pessoa Caio Bezerra Machado Deivide de Sousa Oliveira Manoel Odorico de Moraes Filho Maria Elisabete Amaral de Moraes André Salim Khayat Caroline Aquino Moreira-Nunes

Circadian rhythms (CRs) are a key biological system regulating physiological processes such as metabolism, cell growth, DNA repair, and immunity, adapting to environmental changes like the light/dark cycle. Governed by internal clocks, it modulates gene expression through feedback loops involving Clock Genes (CGs), with the cycle initiated by CLOCK–BMAL1 and NPAS2–BMAL1 heterodimers. Disruptions in circadian rhythms have been linked to diseases including metabolic disorders, neurodegeneration, and cancer. CIPC (CLOCK-interacting pacemaker) has been studied as a negative regulator of the CLOCK–BMAL1 complex, focusing on its role in cancer, particularly leukemias. Public datasets and bioinformatics tools were used to examine CIPC gene expression in healthy patients and acute myeloid leukemia (AML) samples. Our analysis revealed significant overexpression of CIPC in AML compared to healthy tissues (p < 0.0001 ****). Additionally, survival analysis indicated significant differences in overall survival based on CIPC expression, with a log-rank test p-value = 0.014, suggesting that CIPC expression may affect overall patient survival. Altered CIPC expression may contribute to leukemogenesis by inhibiting circadian genes, which are often disrupted in leukemia. Furthermore, CIPC interacts with oncogenic pathways, including the MAPK/ERK pathway, which is essential for cell proliferation. Additional studies are needed to validate these findings and explore the detailed role of CIPC in cancer development.

Clocks & Sleep doi: 10.3390/clockssleep7030032

Authors: Francesca Campoli Francesca Orofino Giuseppe Messina Donatella Di Corrado Vincenzo Cristian Francavilla

Background. Sleep disorders are a group of conditions that disrupt normal sleep patterns and are among the most common clinical challenges faced today. An innovative device that employs nanotechnology to deliver beneficial effects on the human body is the Taopatch® (Tao Technologies, Vedelago, Italy). This study aims to assess the effectiveness of such nanotechnology-based devices in improving sleep quality. Methods. This study included only female participants, as a review of the literature indicated that sleep disorders are more prevalent in women than in men. A total of 30 subjects (with a mean age of 44.8 ± 3.44 years) were randomly divided into two groups: an experimental group and a control group. Sleep quality was evaluated three times throughout the study for each participant using the Pittsburgh Sleep Quality Index (PSQI). The Taopatch® devices were applied using a specialized pillow. Results. The experimental group showed significantly better sleep quality (p < 0.001) compared to the control group. Conclusions. Our findings suggest that the application of the Taopatch® has a positive impact on sleep quality by optimizing posture, aligning the cervical spine, and promoting muscle relaxation. This device uses advanced nanotechnology to enhance various physiological functions, contributing to better overall well-being.

Clocks & Sleep doi: 10.3390/clockssleep7030031

Authors: Abdelmajid Lkoul Keltouma Oum’barek Mohamed Amine Baba Asmaa Jniene Tarek Dendane

Introduction: For patients in intensive care units, the Richards–Campbell Sleep Questionnaire (RCSQ) seems to be a useful tool for assessing sleep quality. However, its application in the Moroccan medical context could be limited due to the lack of a dialectal Arabic version for Morocco. This study’s objective was to translate and validate the RCSQ into Arabic for Moroccan speakers. Patients and methods: For this investigation, a cross-sectional design was adopted. The RCSQ was translated and validated into Arabic for Morocco in accordance with the recommendations. For every scale, psychometric properties were computed. The Cronbach’s α coefficient was utilized to evaluate the internal consistency of multi-item measures. Results: The study involved 224 patients, whose mean age was 47 ± 18.3 years. The RCSQ’s internal consistency, or Cronbach’s alpha, was computed, and all dimensions showed good reliability over the 0.92 (0.894–0.983) level. The items demonstrated good reliability and validity, with correlation values larger than 0.4, according to the data. Conclusion: The RCSQ translated into Arabic for Morocco appears to have good psychometric qualities, making it useful for assessing the quality of sleep of patients in intensive care units within Moroccan healthcare settings.

Clocks & Sleep doi: 10.3390/clockssleep7030030

Authors: Ilya A. Solovev Denis A. Golubev Arina I. Yagovkina Nadezhda O. Kotelina

Chronobiotics represent a pharmacologically diverse group of substances, encompassing both experimental compounds and those utilized in clinical practice, which possess the capacity to modulate the parameters of circadian rhythms. These substances influence fluctuations in various physiological and biochemical processes, including the expression of core “clock” genes in model organisms and cell cultures, as well as the expression of clock-controlled genes. Despite their chemical heterogeneity, chronobiotics share the common ability to alter circadian dynamics. The concept of chronobiotic drugs has been recognized for over five decades, dating back to the discovery and detailed clinical characterization of the hormone melatonin. However, the field remains fragmented, lacking a unified classification system for these pharmacological agents. The current categorizations include natural chrononutrients, synthetic targeted circadian rhythm modulators, hypnotics, and chronobiotic hormones, yet no comprehensive repository of knowledge on chronobiotics exists. Addressing this gap, the development of the world’s first curated and continuously updated database of chronobiotic drugs—circadian rhythm modulators—accessible via the global Internet, represents a critical and timely objective for the fields of chronobiology, chronomedicine, and pharmacoinformatics/bioinformatics. The primary objective of this study is to construct a relational database, ChronobioticsDB, utilizing the Django framework and PostGreSQL as the database management system. The database will be accessible through a dedicated web interface and will be filled in with data on chronobiotics extracted and manually annotated from PubMed, Google Scholar, Scopus, and Web of Science articles. Each entry in the database will comprise a detailed compound card, featuring links to primary data sources, a molecular structure image, the compound’s chemical formula in machine-readable SMILES format, and its name according to IUPAC nomenclature. To enhance the depth and accuracy of the information, the database will be synchronized with external repositories such as ChemSpider, DrugBank, Chembl, ChEBI, Engage, UniProt, and PubChem. This integration will ensure the inclusion of up-to-date and comprehensive data on each chronobiotic. Furthermore, the biological and pharmacological relevance of the database will be augmented through synchronization with additional resources, including the FDA. In cases of overlapping data, compound cards will highlight the unique properties of each chronobiotic, thereby providing a robust and multifaceted resource for researchers and practitioners in the field.

Clocks & Sleep doi: 10.3390/clockssleep7030029

Authors: Michael J. Nelson Darien A. Yu Augustine V. H. Ha Mark R. Wakefield Yujiang Fang

Sleep is an essential part of everyday life and disturbed sleep can produce numerous deleterious effects on the body. An especially prevalent and detrimental subset of sleep disturbances are sleep disturbances that occur in patients during the postoperative period. To better understand these disorders and how to treat them, a literature search was conducted to identify and consolidate recent advancements in this field. This narrative review discusses the structure of a typical night of sleep and the causes, effects, and treatment strategies of Postoperative Sleep Disturbances (PSDs). Factors that contribute to the development of PSDs have been identified at all stages of the surgical process, including the preoperative, intraoperative, and postoperative timepoints. Exposure to these factors can accumulate during each step and may decrease the quality of sleep postoperatively. The development of PSDs has been found to affect multiple systems throughout the body and can ultimately lead to poorer recovery times and increased postoperative mortality. As a result, multiple therapeutic approaches are being investigated for their role in reducing the prevalence of these disorders. This has revealed promising interventions throughout the surgical process, such as preoperative nerve blocks, intraoperative infusions, and postoperative behavioral interventions. However, despite these successful findings, work still needs to be completed to optimize these techniques and generalize intervention strategies.

Clocks & Sleep doi: 10.3390/clockssleep7020028

Authors: Teru Kamogashira Tatsuya Yamasoba Shu Kikuta Kenji Kondo

Measurement of respiratory patterns during sleep plays a critical role in assessing sleep quality and diagnosing sleep disorders such as sleep apnea syndrome, which is associated with many adverse health outcomes, including cardiovascular disease, diabetes, and cognitive impairments. Traditional methods for measuring breathing often rely on expensive and complex sensors, such as polysomnography equipment, which can be cumbersome and costly and are typically confined to clinical settings. These factors limit the performance of respiratory monitoring in routine settings and prevent convenient and extensive screening. Recognizing the need for accessible and cost-effective solutions, we developed a portable sleep sensor that uses an electret condenser microphone (ECM), which is inexpensive and easy to obtain, to measure nasal airflows. Constant current circuits that bias the ECM and circuit constants suitable for measurement enable special uses of the ECM. Furthermore, data transmission through the XBee wireless communication module, which employs the ZigBee short-range wireless communication standard, enables highly portable measurements. This customized configuration allows the ECM to detect subtle changes in airflow associated with breathing patterns, enabling the monitoring of respiratory activity with minimal invasiveness and complexity. Furthermore, the wireless module not only reduces the size and weight of the device, but also facilitates continuous data collection during sleep without disturbing user comfort. This portable wireless sensor runs on batteries, providing approximately 50 h of uptime, a ±50 Pa pressure range, and 20 Hz real-time sampling. Our portable sleep sensor is a practical and efficient solution for respiratory monitoring outside of the traditional clinical setting.

Clocks & Sleep doi: 10.3390/clockssleep7020027

Authors: Anna Giertz Johan Mesterton Tanja Jakobsson Stephen Crawford Somraj Ghosh Anne-Marie Landtblom

In the original publication [...]

Clocks & Sleep doi: 10.3390/clockssleep7020026

Authors: Linn Nyjordet Evanger Ingvild West Saxvig Ståle Pallesen Michael Gradisar Stein Atle Lie Bjørn Bjorvatn

This study explored whether sleep duration, insomnia, social jetlag, and circadian preference predicted adolescents’ risk of anxiety and depression two years later. High school students initially aged 16–17 years were, in 2019 and 2021, invited to a web-based survey assessing sleep patterns, insomnia, circadian preference, anxiety, and depression. Sleep duration, insomnia, circadian preference, depression, and anxiety were assessed using the Munich ChronoType Questionnaire, the Bergen Insomnia Scale, the reduced Morningness–Eveningness Questionnaire, the Patient Health Questionnaire-9, and the Generalized Anxiety-Disorder 7, respectively. Analyses were conducted using logistic regression analyses. The analytic longitudinal sample comprised 1456 students (initial mean age 16.4 years; 61.4% girls). Short school night sleep duration, chronic insomnia, and more severe insomnia symptoms at baseline predicted greater risk of anxiety and depression at follow-up when controlled for anxiety and depression at baseline. Neither free night sleep duration nor social jetlag at baseline were related to the risk of anxiety and depression at follow-up. When circadian preference was investigated continuously, greater morningness at baseline predicted lower risk of anxiety and depression at follow-up. When circadian preference was investigated categorically, evening preference type was associated with higher risk of depression at follow-up than intermediate preference type, while the prospective risk of anxiety and depression otherwise did not differ in relation to circadian preference. The results attest to prospective associations between adolescent sleep problems at baseline and later risk of anxiety and depression.

Clocks & Sleep doi: 10.3390/clockssleep7020025

Authors: Azusa Ono Yoshiko Iwatani Arika Yoshizaki Tomoko Nishimura Ikuko Mohri Kuriko Kagitani-Shimono Masako Taniike

This study explored the impact of lifestyle habits and sensory processing patterns on sleep quality by analyzing body movements (BMs) during the first and last 3 h of sleep in toddlers. We collected cross-sectional data about sleep-related habits from 58 toddlers using a mobile application. Actigraphy measured BMs during nighttime sleep and 1 h before bedtime, as well as sleep latency, over 8 consecutive days. The Infant/Toddler Sensory Profile was used to assess the toddlers’ sensory processing patterns. The participants had a mean age of 22.0 ± 2.0 months. BMs were significantly lower during the first 3 h of sleep. Longer sleep latency was significantly associated with media use and higher activity levels before bedtime. Ending a nap earlier and consuming a substantial breakfast were correlated with lower BMs during the first 3 h of sleep. Auditory and oral sensory scores were positively correlated with BMs during the first 3 h of sleep. However, no specific factors related to lifestyle habits or sensory processing patterns were found to correlate with BMs during the last 3 h of sleep. Lifestyle habits and sensory processing patterns have a significant impact on toddlers’ sleep quality, emphasizing the importance of appropriate routines and environments.

Clocks & Sleep doi: 10.3390/clockssleep7020024

Authors: Tanja Grünberger Christopher Höhn Manuel Schabus Belinda Angela Pletzer Anton-Rupert Laireiter

Shift workers are at increased risk of insomnia. The standard treatment (cognitive behavioral therapy for insomnia) poses significant challenges for this demographic due to irregular work and sleep schedules. New approaches are still considered insufficient due to high attrition or insufficient effectiveness. Our preliminary study identified sleep-relevant state and trait factors (see secondary outcomes) for incorporation into an innovative manual that addresses sleep in an implicit manner. The objective was to reduce the focus on insomnia and to replace regularity-based interventions. With a sample of 55 insomniacs (67.74% male, mean age 41.62 years), standard and customized treatments were compared using pre-treatment, post-treatment, and three-month follow-up measurements (RCT, self-assessment data). Our linear mixed models revealed the main significant effects of the measurement point for the primary (insomnia severity, sleep quality, sleep onset latency, total sleep time, daytime sleepiness) and the secondary outcomes (selection: anxiety/depression, dysfunctional beliefs, arousal, emotional stability, concern). No main effects of the condition or interaction effects were identified. Non-inferiority and equivalence tests demonstrated that the customized treatment is equivalent to standard therapy, which is a favorable outcome in light of the implicit approach. Consequently, this innovative approach warrants further exploration, incorporating the present results.

Clocks & Sleep doi: 10.3390/clockssleep7020023

Authors: Dietmar Ausserhofer Giuliano Piccoliori Adolf Engl Pasqualina Marino Verena Barbieri Stefano Lombardo Timon Gärtner Christian J. Wiedermann

It remains unclear how sleep health has developed in the general population after the COVID-19 pandemic. This study aimed to (1) investigate the prevalence of sleep problems and poor sleep quality and (2) explore the associated sociodemographic and health-related factors in South Tyrol, Italy. A cross-sectional, population-based survey was conducted with a stratified probabilistic sample of 4000 adults aged ≥ 18 years. Sleep quality was assessed using the brief version of the Pittsburgh Sleep Quality Index. Descriptive and logistic regression analyses were performed to analyze the data. A total of 2090 adults (53%) completed the survey. Poor sleep quality was reported by 17.8%, with 28.2% of participants reporting insufficient sleep duration (i.e., six hours or less), 12.7% having problems staying asleep (i.e., waking up to 3–4 times a week and unable to fall asleep again), and 8.7% having problems falling asleep (i.e., >30 min). Sleep problems and poor sleep quality were associated with sociodemographic and health-related factors, including gender, age, mother tongue, chronic disease, and sleep hygiene. Notably, Italian-speaking participants reported poorer sleep quality and greater difficulty staying asleep compared to German-speaking participants, highlighting potential sociocultural influences on sleep health. This study contributes to understanding the unique sleep health challenges in a multilingual region, highlighting the role of sociocultural factors in sleep quality differences between language groups.

Clocks & Sleep doi: 10.3390/clockssleep7020022

Authors: Matteo Conenna Camille Point Benjamin Wacquier Jean-Pol Lanquart Matthieu Hein

Considering the frequent co-occurrence of major depressive disorder and excessive daytime sleepiness in apneic individuals, this study aimed to explore the relationship between excessive daytime sleepiness and the risk of developing major depressive disorder in this specific subpopulation. Demographic and polysomnographic data were retrospectively extracted from the clinical database of 1849 apneic individuals at the Sleep Unit. Excessive daytime sleepiness was considered present when the Epworth Sleepiness Scale score was >10 and major depressive episodes were diagnosed according to DSM criteria. Logistic regression analyses were performed to assess the risk of major depressive disorder associated with excessive daytime sleepiness in apneic individuals. The prevalence of major depressive disorder was 26.3% in apneic individuals. After controlling for major confounding variables, multivariate logistic regression analyses revealed that apneic individuals with complaints of excessive daytime sleepiness had a higher likelihood of developing major depressive disorder compared to those without complaint of excessive daytime sleepiness. This study highlights the strong association between excessive daytime sleepiness and major depressive disorder in apneic individuals, underlining the importance of systematically assessing and adequately treating excessive daytime sleepiness to better manage depressive symptoms and improve overall treatment outcomes in this specific subpopulation.

Clocks & Sleep doi: 10.3390/clockssleep7020021

Authors: Chandima P. Karunanayake Charlene Thompson Meera J. Kachroo Donna C. Rennie Warren Seesequasis Jeremy Seeseequasis James A. Dosman Mark Fenton Vivian R. Ramsden Malcolm King Sylvia Abonyi Shelley Kirychuk Niels Koehncke Punam Pahwa

Sleep is essential for maintaining both mental and physical well-being. It plays a critical role in the health and development of children. This study investigates sleep patterns and habits of First Nations children, the prevalence of sleep disturbances, and excessive daytime sleepiness (EDS), along with the factors associated with EDS. Our 2024 First Nations Children Sleep Health Study assessed the sleep health of children aged 6 to 17 years living in a First Nation in Canada. Statistical analyses were performed using comparison tests and logistic regression models. A total of 78 children participated; 57.7% were boys. The average age of the participants was 10.49 years (SD = 3.53 years). On school days, children aged 6 to 9 years slept an average of one additional hour, while on weekends, they slept an extra 40 min compared to adolescents aged 10 to 17 years. Only 39.7% of the children (ages 6 to 17) slept alone in a room, with more than 80% of the children sharing a bed every night. Only 30.6% of the children aged 6 to 9 years and 7.2% of the adolescents aged 10 to 17 years adhered to the recommended maximum screen time of 2 h on school days. More than two-thirds of the children reported experiencing sleep disturbances. The prevalence of EDS was 19.7%. After adjusting for age and sex, it was determined that the children who snored loudly and those who did not sleep in their own beds were more likely to experience abnormally high levels of daytime sleepiness. A high proportion of children exceeded the recommended screen time, an important public health issue. Further, identifying sleep patterns among children will facilitate the diagnosis and treatment of disordered sleep.

Clocks & Sleep doi: 10.3390/clockssleep7020020

Authors: Larissa Quintão Guilherme Julia Pagotto Matos Ana Claudia Pelissari Kravchychyn Marco Tulio De Mello Paulo Roberto dos Santos Amorim Helton de Sá Souza

Trail running has seen a surge in participants, including individuals with disabilities, particularly in ultratrail running (UTRs). Sleep–wake patterns are crucial for optimal performances in UTRs, which present unique physiological and behavioral challenges. This case study evaluated the sleep–wake cycle of a blind trail ultramarathoner (BTR) and his guide (GTR) before, during, and after an 80 km UTR. Two male participants (BTR: 54 years, BMI: 26.1 kg/m2; GTR: 48 years, BMI: 24.2 kg/m2) were assessed using validated questionnaires (MEQ, ESS, ISI, and PSQI) and actigraphy over 35 days. The BTR exhibited a morning chronotype (MEQ = 63), mild insomnia (ISI = 11), poor sleep quality (PSQI = 5), and prolonged sleep latency (>60 min), while the GTR showed an indifferent chronotype (MEQ = 52), good sleep quality (PSQI = 3), and shorter latency (10 min). Post-competition, both athletes experienced an increased total sleep time (TST): the BTR by 17.8% (05:32:00 vs. 04:25:00) and the GTR by 5.5% (07:01:00 vs. 06:39:00). The BTR demonstrated a greater Wakefulness after sleep onset (WASO 01:00:00 vs. 00:49:00) and awakenings (15.4 vs. 6.1). A time series analysis revealed greater variability in the BTR’s post-competition sleep efficiency and TST, while the GTR exhibited a greater stability of the circadian phase. These findings highlight the intricate sleep challenges faced by blind athletes, informing strategies to optimize recovery and performance.

Clocks & Sleep doi: 10.3390/clockssleep7020019

Authors: Yong-Woo Shin Jung-Ick Byun Jun-Sang Sunwoo Chae-Seo Rhee Jung-Hwan Shin Han-Joon Kim Ki-Young Jung

Isolated rapid eye movement (REM) sleep behavior disorder (iRBD) is recognized as a precursor to neurodegenerative diseases. This study aimed to develop predictive models for the timing and subtype of phenoconversion in iRBD. We analyzed comprehensive clinical data from 178 individuals with iRBD over a median follow-up of 3.6 years and applied machine learning models to predict when phenoconversion would occur and whether progression would present with motor- or cognition-first symptoms. During follow-up, 30 patients developed a neurodegenerative disorder, and the extreme gradient boosting survival embeddings–Kaplan neighbors (XGBSE-KN) model demonstrated the best performance for timing (concordance index: 0.823; integrated Brier score: 0.123). Age, antidepressant use, and Movement Disorder Society–Unified Parkinson’s Disease Rating Scale Part III scores correlated with higher phenoconversion risk, while coffee consumption was protective. For subtype classification, the RandomForestClassifier achieved the highest performance (Matthews correlation coefficient: 0.697), indicating that higher Montreal Cognitive Assessment scores and younger age predicted motor-first progression, whereas longer total sleep time was associated with cognition-first outcomes. These findings highlight the utility of machine learning in guiding prognosis and tailored interventions for iRBD. Future research should include additional biomarkers, extend follow-up, and validate these models in external cohorts to ensure generalizability.

Clocks & Sleep doi: 10.3390/clockssleep7020018

Authors: Garrett R. Augsburger Eric J. Sobolewski Guillermo Escalante Austin J. Graybeal

This narrative review explores the intricate relationship between circadian regulation and exercise performance, emphasizing the importance of aligning training strategies with the body’s natural physiological fluctuations. The three key mechanisms investigated are temperature, hormonal fluctuations, and diurnal chronotype—an individuals’ exhibition of enhanced physical or cognitive performance at specific times of day. Core body temperature variations impact exercise performance, suggesting strategic workout timing and intensity adjustments. Hormonal patterns (i.e., insulin, cortisol, testosterone) influence energy metabolism and muscle growth, informing tailored training plans. Diurnal chronotypes significantly affect performance, advocating for personalized training sessions based on individual preferences and entrained awakening. Integrating circadian mechanisms into training offers strategic advantages, guiding practitioners to design effective, personalized regimens, though we acknowledge relevant challenges and the need for further research.

Clocks & Sleep doi: 10.3390/clockssleep7020017

Authors: Marine Dourte Gregory Hammad Christina Schmidt Philippe Peigneux

Ageing is associated with alterations in circadian rhythms and thermoregulation, contributing to a fragmentation of the sleep–wake cycle and possibly age-related changes in cognitive performance. In this study, we investigated the relationship between visuo-spatial working memory (vsWM) performance and thermoregulation in young (18–34 years) and old (64–84 years) healthy human adults. Variations in the distal–proximal skin temperature gradient (DPG) were continuously monitored over the 24 h cycle in a field setting. vsWM was assessed during morning (09:00) and evening sessions (17:00) using an object–location binding task. As expected, a reduced circadian DPG amplitude was observed in old as compared to young participants. Likewise, old participants produced more errors than the young ones in object identification and location, suggesting reduced vsWM ability. Notwithstanding this, no significant association was found between circadian DPG modulation and vsWM performance, nor between testing time-of-day and cognitive performance. Further research is needed to explore environmental factors and the timing of peak circadian rhythms to better understand the interplay between circadian biology and cognitive ageing.

Clocks & Sleep doi: 10.3390/clockssleep7010016

Authors: Gabrielle Rigney Matthew Browne Charli Sargent Michele Lastella

The aim of this study was to examine sleep timing across the lifespan of Australian adults. A cross-sectional design was used to collect information on subjective sleep timing from 1225 participants (52.3% female) during a telephone interview. The participants were aged from 18 to over 80 and were grouped according to their age using 10-year increments (e.g., 18–29 y, 30–39 y, etc.). There was a diverse distribution across the lifespans, with the largest proportion of participants being from the 60–69 age group (22.8%). Participants were predominantly from New South Wales, Queensland, and Victoria. Younger adults reported going to bed later (p < 0.001) and waking up later than other age groups (p < 0.001). Wake times were earliest during middle adulthood (p < 0.001). There was no significant age effect on the minimum sleep required for good health (p = 0.159) and only a marginal decrease with age in the amount of sleep required to maintain a good mood (p = 0.041). In conclusion, these findings highlight significant variations in sleep timing across younger, middle-aged, and older Australian adults. The current findings could inform future Australian sleep health campaigns, in which the goal is to provide targeted strategies for age groups across their lifespans.

Clocks & Sleep doi: 10.3390/clockssleep7010015

Authors: David Negelspach Kathryn E. R. Kennedy Alisa Huskey Jungwon Cha Anna Alkozei William D. S. Killgore

The regularity of sleep–wake cycles is a defining characteristic of normative sleep patterns that are typically associated with proper circadian rhythmicity. The previous literature indicates that consistent patterns of sleep and wake are associated with improved sleep quality and cognitive functioning. Conversely, sleep irregularity has been associated with reduced well-being and inefficiency in resting-state neural networks. This study investigated the relationship between specific sleep regularity measures and outcomes, including emotional affect, sleep quality, and resting-state functional connectivity. We found that variability in wake onset predicted poorer sleep quality and reduced positive affect. Furthermore, sleep regularity measures were associated with altered functional connectivity between the posterior cingulate cortex and regions involved in emotional processing. We propose that alterations in default mode network (DMN) connectivity linked to sleep irregularity reflect disruptions in emotional processing and sleep quality.

Clocks & Sleep doi: 10.3390/clockssleep7010014

Authors: Jürgen Degenfellner Susanne Strohmaier Magdalena Zebrowska Ingvild Saksvik-Lehouillier Eva Schernhammer

Shift Work Sleep Disorder (SWSD) is a significant and highly prevalent condition affecting up to 48% of individuals with irregular work schedules. The diagnostic criteria for SWSD include persistent insomnia or sleepiness in relation to shift work, not attributable to other disorders or external factors. To explore risk factors of SWSD, we conducted a cross-sectional analysis among 10,787 night shift workers in the UK Biobank. To determine correlates of SWSD using multivariable-adjusted logistic regression models, a preselection of potential risk factors was made on the basis of previous literature. Self-identifying as ‘Asian or Asian British’ or ‘Black or Black British’ (compared to being ‘White’), male sex, and high scores on sociability, warmth and diligence were associated with lower odds for SWSD. We did not find significant associations of chronotype, frequency of alcohol intake, smoking, and time employed in current job with SWSD. These findings underscore the need for targeted interventions and workplace policies to mitigate the adverse effects of SWSD. Future research should aim to explore the mechanisms behind these associations and develop strategies to enhance shift work tolerance among night shift workers.

Clocks & Sleep doi: 10.3390/clockssleep7010013

Authors: Sergio Garbarino Antonella Bodini Saverio Sabina Carlo Giacomo Leo Pierpaolo Mincarone Antonella Rissotto Stanislao Fusco Roberto Guarino Maria Rosaria Tumolo Giovanni Luigi Tripepi Egeria Scoditti Nicola Magnavita

The COVID-19 outbreak has changed work organization in favor of a working from home (WH) modality. We examined the association of WH during the pandemic with sleep health in workers of a public research organization. An online cross-sectional survey in 2022 at the National Research Council of Italy collected information on sociodemographics, work characteristics, and sleep pattern during WH compared with before WH. In the whole sample (n = 748), total sleep quality did not significantly change. Excessive daytime sleepiness (EDS) decreased during WH. Total sleep quality increased during WH in poor sleepers, while it decreased in good sleepers. The morning chronotype was protective against sleep worsening in poor sleepers. Risk factors were depression in poor and good sleepers, and increased daytime sleepiness and body weight gain in good sleepers. These findings emphasize the importance of baseline sleep pattern in shaping the impact of WH on sleep.

Clocks & Sleep doi: 10.3390/clockssleep7010012

Authors: Tim J. A. Vaessen Ruth E. Mark Sebastiaan Overeem Margriet M. Sitskoorn

This study examined the nature, severity, and predictors of cognitive complaints in patients referred for suspected obstructive sleep apnea (OSA). The sample included 127 patients classified as no OSA (AHI, apnea/hypopnea index < 5, N = 32), mild OSA (AHI 5–15, N = 46), moderate OSA (AHI 15–30, N = 25), or severe OSA (AHI > 30, N = 24), and 53 healthy controls (HCs), matched for age, sex, education, and IQ. Cognitive complaints were assessed using the Cognitive Failure Questionnaire (CFQ) and the Behavioral Rating Inventory of Executive Functioning Adult Version (BRIEF-A). Regression analyses examined predictors of cognitive complaints including AHI, sleepiness, anxiety, depression, fatigue, and neuropsychological performance. Compared to HCs, those with mild OSA reported more forgetfulness, distractibility, and working memory issues, while those with severe OSA reported more difficulties with initiative, both with large effect sizes. Cognitive complaints were linked to sleepiness, anxiety, and fatigue (ß’s 0.29–0.37), but not AHI or cognitive performance. Cognitive complaints were not specific to subjects with OSA but were also common among individuals with sleep complaints suspected for OSA. In conclusion, cognitive complaints were associated with anxiety, fatigue, and sleepiness rather than objective cognitive performance or impairment.

Clocks & Sleep doi: 10.3390/clockssleep7010011

Authors: Shahab Haghayegh Ramon C. Hermida Michael H. Smolensky Mili Jimenez Gallardo Claudia Duran-Aniotz Andrea Slachevsky Maria Isabel Behrens David Aguillon Hernando Santamaria-Garcia Adolfo M. García Diana Matallana Agustín Ibáñez Kun Hu

Growing evidence suggests that abnormal diurnal blood pressure rhythms may be associated with many adverse health outcomes, including increased risk of cognitive impairment and dementia. This study evaluates methodological aspects of research on bidirectional associations between ambulatory blood pressure monitoring (ABPM) patterns and cognitive function. By examining the 28 recent studies included in a recent systematic review on the association between ABPM patterns with cognitive function and risk of dementia, our review revealed several significant limitations in study design, sample characteristics, ABPM protocol, cognitive assessment, and data analysis. The major concerns include a lack of diversity in study populations with underrepresentation of Blacks and Latinos, a predominant focus on Alzheimer’s disease or all-cause dementia without distinguishing other dementia subtypes, different and not standardized measures of cognition or dementia, prevalent use of 24 h monitoring without considering the adaption effect, inconsistent definitions of dipping status, and ignorance of individual differences in timings of daily activities such as bed and awakening times. In addition, confounding variables such as class, dose, and timing of antihypertensive medication are inadequately controlled or considered. Further, longitudinal studies were scarce examining the bidirectional relationship between ABPM patterns and cognitive decline over time. Collectively, these deficiencies undermine the reliability and generalizability of current findings. Addressing these methodological challenges is crucial for a more comprehensive understanding of diurnal blood pressure rhythms in diverse populations and for developing an evidence-based guideline for ambulatory monitoring and control of blood pressure across the sleep-wake cycle to prevent cognitive decline and dementia.

Clocks & Sleep doi: 10.3390/clockssleep7010010

Authors: Waléria D. P. Gusmão Aline Silva-Costa Victor M. Silva Claudia R. C. Moreno

Cardiovascular diseases are the leading cause of morbidity and mortality worldwide. These conditions, characterized by multifactorial etiology, are associated with arterial stiffness, and adequate sleep serves as a preventive factor. Professionals engaged in night work are at an increased risk of premature vascular aging due to potential disruption of the sleep–wake cycle and sleep restriction. The aim of this study was to assess the relationship between duration of exposure to night work and arterial stiffness in nursing professionals. A total of 63 nursing professionals working rotating shifts participated in the study. Arterial stiffness was measured using oscillometric pulse wave velocity, and sleep–wake patterns were monitored using actigraphy. Path analysis revealed no direct association between duration of night work exposure and arterial stiffness in the professionals studied. However, an increase of 1 standard deviation (SD) in social jet lag duration was significantly associated with a 0.212 SD increase in perceived stress (p = 0.047). Furthermore, an increase of 1 SD in social jet lag duration was significantly associated with a 0.093 SD increase in the highest pulse wave velocity (p = 0.034). Thus, an association was found between increased social jet lag and elevated pulse wave velocity, an independent predictor of higher cardiovascular risk.

Clocks & Sleep doi: 10.3390/clockssleep7010009

Authors: Caterina Leitner Viviana Greco Francesca Casoni Penelope A. Lewis Luigi Ferini-Strambi Andrea Galbiati

(1) Background: Phasic events in rapid eye movement (REM) sleep are a core feature of isolated REM behavior disorder (iRBD), which is often associated with emotion dysregulation. This study explores the relationship between sleep and the overnight habituation of emotional reactivity in healthy controls (HCs) and iRBD patients, focusing on the role of REM phasic events and a specific non-REM waveform, namely sleep spindles. (2) Methods: Participants underwent polysomnography and completed arousal rating tasks and mood scales before and after sleep. In total, eight HCs (4 M, mean age 60.62 ± 6.8) and eight iRBD patients (7 M, mean age 68.25 ± 5.12) were included in the analyses. (3) Results: In HCs, longer REM sleep duration correlated positively with overnight habituation. In the whole sample, overnight habituation negatively correlated with REM sleep latency and wake-after-sleep onset, and positively with N2 sleep. Higher overnight habituation was associated with fewer REM arousals and awakenings in the whole sample, and with greater N2 sleep spindle density in HCs. (4) Conclusions: Our preliminary results suggest that REM sleep and spindles in N2 play critical roles in emotional processing. The study confirms the relationship between emotion dysregulation and REM phasic events, enhancing our understanding of how sleep impacts emotional reactivity and also in the prodromal phase of neurodegenerative disease.

Clocks & Sleep doi: 10.3390/clockssleep7010008

Authors: Anna Giertz Johan Mesterton Tanja Jakobsson Stephen Crawford Somraj Ghosh Anne-Marie Landtblom

Background: Narcolepsy impacts both patients and society, yet there is limited data on its socioeconomic consequences. Methods: This retrospective longitudinal cohort study used pseudonymized patient-level data from Swedish registers and included narcolepsy patients from January 2015–December 2019 and age–sex matched controls. All patients received an index date corresponding to their first narcolepsy diagnosis. Results: This study included 466 incident narcolepsy patients and 2330 matched controls. During the years studied, healthcare resource utilization was 2–5 times higher for incident narcolepsy patients compared to matched controls (p < 0.0001). Modafinil, stimulants, and antidepressants were prescribed more often to incident narcolepsy patients (p < 0.0001). Work productivity was significantly impacted, as incident narcolepsy patients took 7.0–10.5 more sick leave days than their matched controls (p < 0.0001) and had an average of 14.8 net days of disability leave (associated with indirect costs of EUR 1630) versus only 5.8 days among matched controls (EUR 638) during the year of the index (p = 0.027). After controlling for age, sex, and the Charlson comorbidity index, the odds of disability leave were 3.3 times higher in incident narcolepsy patients. Conclusions: This study provides evidence of the magnitude of the substantial societal economic burden due to narcolepsy in Sweden, evidenced by higher healthcare resource utilization and indirect costs.

Clocks & Sleep doi: 10.3390/clockssleep7010007

Authors: Mariana Marchesano Alejandra Carboni Bettina Tassino Ana Silva

Time-of-day and individual circadian variability influence cognitive performance, with later chronotypes being most compromised earlier in the day. On the other hand, moderate-intensity exercise has been shown to enhance cognitive function. We sought to evaluate the interplay among circadian rhythms, exercise, and cognitive performance in 22 students from the Uruguayan National Dance School, a population previously characterized as late chronotypes, attending a demanding morning schedule. We assessed sleep habits and physical activity patterns using self-report questionnaires and actigraphy. Before and after morning training, participants completed a psychomotor vigilance task (PVT) and a visual Stroop task (congruent and incongruent). The reaction speeds were lower early in the morning than at noon for all these tasks. We also found (1) a positive correlation between weekend sleep duration and PVT performance before training but not after; (2) a negative correlation between individual circadian phase and Stroop performance for both congruent and incongruent conditions after training but not before; and (3) a better Stroop performance after training for both congruent and incongruent conditions in dancers who engaged longer moderate-intensity exercise during training. Our findings suggest that regular morning training might help mitigate cognitive impairments experienced by dancers with later chronotypes in challenging morning scenarios.

Clocks & Sleep doi: 10.3390/clockssleep7010006

Authors: María del Rosario Ayala-Moreno Paola Andrea Martínez-Serrano Montserrat Alheli Melgarejo-Gutiérrez Alma Rosa Hernández-Mondragón Azucena Martínez-Basila Araceli Martínez-Coronado María José Losana-Valencia Esther Vargas-Medina Eloisa Colín-Ramírez Adriana Benítez-Rico

Home confinement due to Coronavirus Disease 2019 (COVID-19) led to lifestyle changes that increased sleep disturbances, particularly in areas with higher infection and mortality rates. This study is a retrospective study based on data collected through an online survey conducted during the COVID-19 confinement. It aims to analyze changes in sleep quantity and quality and their association with lifestyle changes in the metropolitan area of Mexico City. A total of 899 adults from this area completed an online questionnaire between June 2020 and February 2021. This study assessed sleep quantity, sleep quality, insomnia symptoms, and lifestyle changes during the confinement period. Results showed that sleep quantity increased (7.10 ± 1.37 vs. 7.43 ± 1.42 h, p < 0.0001), with more participants, especially young adults and women, reporting later bed and wake-up times. The Pittsburgh Sleep Quality Index increased by 1.4 units, with poor sleep quality associated with lifestyle during confinement. Insomnia symptoms, sleep latency, and poor sleep quality also increased, particularly in women. Males and those without chronic comorbidities were less likely to experience poor sleep quality, while tobacco use and later bedtimes increased this risk. This study concludes that, while sleep quantity increased, sleep quality declined, particularly among young adults, women, and those with unhealthy lifestyles. These findings could guide sleep health initiatives tailored to specific lifestyle changes in different population groups.

Clocks & Sleep doi: 10.3390/clockssleep7010005

Authors: Suguru Nakajima Yuichiro Otsuka Yoshitaka Kaneita Osamu Itani Yuki Kuwabara Aya Kinjo Ruriko Minobe Hitoshi Maesato Susumu Higuchi Hideyuki Kanda Hisashi Yoshimoto Maki Jike Hideaki Kasuga Teruna Ito Yoneatsu Osaki

It is unclear whether patterns of alcohol consumption are associated with sleep disturbance. We aimed to investigate the relationship between comprehensive alcohol-related factors and insomnia symptoms, as well as sleep quality, among adult women in Japan. Responses to an online cross-sectional survey were gathered from 12,000 women. The survey items included demographic characteristics, alcohol consumption (Alcohol Use Disorders Identification Test, nightcaps, years of drinking), sleep-related factors (sleep duration, insomnia symptoms, sleep quality), lifestyle-related factors, and mental health. Binary logistic regression was used to investigate the relationship between alcohol consumption and both insomnia symptoms and sleep quality. A total of 10,233 women were included in the final analysis. The results revealed that several alcohol-related behaviors, including the consumption of nightcaps and years of drinking, were significantly associated with insomnia symptoms and poor sleep quality. Specifically, nightcaps were significantly associated with all types of insomnia symptoms and poor sleep quality, with a higher odds ratio than other alcohol-related items. Our findings suggest that specific alcohol-related behaviors, particularly the consumption of nightcaps, are associated with insomnia symptoms and poor sleep quality among women. Intervention programs for alcohol consumption should be provided to prevent sleep problems among women.

Clocks & Sleep doi: 10.3390/clockssleep7010004

Authors: Dean W. Beebe Andrea L. Fidler Laura McLaughlin Sabrina Grove Stephanie J. Crowley

Despite extensive research on the effects of sleep restriction on adolescent health, the field lacks experimental methods to study the health effects of mistimed sleep, which is also common among adolescents. This paper describes a novel 3-week experimental protocol that was designed to compare sleep restriction, like what many adolescents experience on school nights, against sleep that meets the recommended duration but is timed to be relatively aligned or misaligned with their circadian phase. Healthy 14–18-year-olds, classified as early (“Lark”) and late (“Owl”) chronotypes, entered a six-night chronotype-aligned stabilization condition, followed by five nights of sleep restriction, a return to the stabilization schedule, and five nights of healthy sleep duration (HS). During HS, participants were randomly assigned to early-to-bed versus late-to-rise arms, intended to align with or misalign with their circadian phase. Actigraphy monitored sleep, and weekly dim-light melatonin onset (DLMO) assessed circadian phase. Analyses confirmed that the protocol met five key validation metrics related to differential attrition, sleep timing, circadian phase, and experimental induction of HS that is timed to be relatively aligned vs. misaligned with circadian phase. This protocol appears useful for future research into how misaligned sleep patterns, which occur regularly for many adolescents, may impact health.