Journal Description
Clocks & Sleep
Clocks & Sleep
is a peer-reviewed, open access journal that investigates a wide range of sleep related topics and is published quarterly online by MDPI. The Australasian Chronobiology Society, Society for Light Treatment and Biological Rhythms, and Swiss Society of Sleep Research, Sleep Medicine and Chronobiology are affiliated with Clocks & Sleep and the society members receive a discount on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High visibility: indexed within Scopus, ESCI (Web of Science), PubMed, PMC, FSTA, and other databases.
- Journal Rank: CiteScore - Q2 (Neuroscience (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 27.3 days after submission; acceptance to publication is undertaken in 4.6 days (median values for papers published in this journal in the first half of 2024).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Journal Clusters-Neurosciences: Brain Sciences, Neurology International, NeuroSci, Clinical and Translational Neuroscience, Neuroglia, Psychiatry International, Clocks & Sleep and Journal of Dementia and Alzheimer's Disease.
Impact Factor:
2.1 (2023);
5-Year Impact Factor:
2.4 (2023)
Latest Articles
Wearable Light Loggers in Field Conditions: Corneal Light Characteristics, User Compliance, and Acceptance
Clocks & Sleep 2024, 6(4), 619-634; https://doi.org/10.3390/clockssleep6040042 - 25 Oct 2024
Abstract
Understanding user challenges with light dosimeters is crucial for designing more acceptable devices and advancing light exposure research. We systematically evaluated the usability and acceptability of a light dosimeter (lido) with 29 participants who wore the dosimeter near the corneal plane of the
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Understanding user challenges with light dosimeters is crucial for designing more acceptable devices and advancing light exposure research. We systematically evaluated the usability and acceptability of a light dosimeter (lido) with 29 participants who wore the dosimeter near the corneal plane of the eye for 5 days. Common reasons for not wearing the dosimeter included exercise, recharging, wet environments, public places, and discomfort. Despite these issues, participants adhered to using the dosimeter with high compliance (89% of recording time). Our findings revealed a significant discrepancy between mean (300 lxmEDI) and median (51 lxmEDI) melanopic equivalent daylight illuminance. This discrepancy indicates that the participants were exposed to significantly lower light levels most of the time. Specifically, participants were exposed to light levels above 250 lxmEDI for only 14% of their wearing time. This highlights the need for increased exposure to recommended light levels. In the evening, participants were exposed to less than the recommended 10 lxmEDI for 58% of their wearing time, which is in line with the guidelines for reducing light exposure before sleep. This study highlights the urgent need for strategies to increase daily light exposure that are more in line with circadian health recommendations.
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(This article belongs to the Section Impact of Light & other Zeitgebers)
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Sleep Fragmentation Modulates the Neurophysiological Correlates of Cognitive Fatigue
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Oumaïma Benkirane, Peter Simor, Olivier Mairesse and Philippe Peigneux
Clocks & Sleep 2024, 6(4), 602-618; https://doi.org/10.3390/clockssleep6040041 - 22 Oct 2024
Abstract
Cognitive fatigue (CF) is a critical factor affecting performance and well-being. It can be altered in suboptimal sleep quality conditions, e.g., in patients suffering from obstructive sleep apnea who experience both intermittent hypoxia and sleep fragmentation (SF). Understanding the neurophysiological basis of SF
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Cognitive fatigue (CF) is a critical factor affecting performance and well-being. It can be altered in suboptimal sleep quality conditions, e.g., in patients suffering from obstructive sleep apnea who experience both intermittent hypoxia and sleep fragmentation (SF). Understanding the neurophysiological basis of SF in healthy individuals can provide insights to improve cognitive functioning in disrupted sleep conditions. In this electroencephalographical (EEG) study, we investigated in 16 healthy young participants the impact of experimentally induced SF on the neurophysiological correlates of CF measured before, during, and after practice on the TloadDback, a working memory task tailored to each individual’s maximal cognitive resources. The participants spent three consecutive nights in the laboratory two times, once in an undisrupted sleep (UdS) condition and once in an SF condition induced by non-awakening auditory stimulations, counterbalanced and performed the TloadDback task both in a high (HCL) and a low (LCL) cognitive load condition. EEG activity was recorded during wakefulness in the 5 min resting state immediately before and after, as well as during the 16 min of the TloadDback task practice. In the high cognitive load under a sleep-fragmentation (HCL/SF) condition, high beta power increased during the TloadDback, indicating heightened cognitive effort, and the beta and alpha power increased in the post- vs. pre-task resting state, suggesting a relaxation rebound. In the low cognitive load/undisturbed sleep (LCL/UdS) condition, low beta activity increased, suggesting a relaxed focus, as well as mid beta activity associated with active thinking. These findings highlight the dynamic impact of SF on the neurophysiological correlates of CF and underscore the importance of sleep quality and continuity to maintain optimal cognitive functioning.
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(This article belongs to the Section Human Basic Research & Neuroimaging)
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Timing Mechanisms for Circadian Seizures
by
Kristina Slabeva and Maxime O. Baud
Clocks & Sleep 2024, 6(4), 589-601; https://doi.org/10.3390/clockssleep6040040 - 21 Oct 2024
Abstract
For centuries, epileptic seizures have been noticed to recur with temporal regularity, suggesting that an underlying biological rhythm may play a crucial role in their timing. In this review, we propose to adopt the framework of chronobiology to study the circadian timing of
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For centuries, epileptic seizures have been noticed to recur with temporal regularity, suggesting that an underlying biological rhythm may play a crucial role in their timing. In this review, we propose to adopt the framework of chronobiology to study the circadian timing of seizures. We first review observations made on seizure timing in patients with epilepsy and animal models of the disorder. We then present the existing chronobiology paradigm to disentangle intertwined circadian and sleep–wake timing mechanisms. In the light of this framework, we review the existing evidence for specific timing mechanisms in specific epilepsy syndromes and highlight that current knowledge is far from sufficient. We propose that individual seizure chronotypes may result from an interplay between independent timing mechanisms. We conclude with a research agenda to help solve the urgency of ticking seizures.
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(This article belongs to the Section Disorders)
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Association of Insomnia with Functional Outcomes Relevant to Daily Behaviors and Sleep-Related Quality of Life among First Nations People in Two Communities in Saskatchewan, Canada
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Chandima P. Karunanayake, James A. Dosman, Najib Ayas, Mark Fenton, Jeremy Seeseequasis, Reynaldo Lindain, Warren Seesequasis, Kathleen McMullin, Meera J. Kachroo, Vivian R. Ramsden, Malcolm King, Sylvia Abonyi, Shelley Kirychuk, Niels Koehncke, Robert Skomro and Punam Pahwa
Clocks & Sleep 2024, 6(4), 578-588; https://doi.org/10.3390/clockssleep6040039 - 12 Oct 2024
Abstract
Insomnia is a common sleep complaint in Canada and is associated with increased use of health care services and economic burden. This paper examines the association of insomnia with functional outcomes relevant to daily behaviors and sleep-related quality of life among First Nations
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Insomnia is a common sleep complaint in Canada and is associated with increased use of health care services and economic burden. This paper examines the association of insomnia with functional outcomes relevant to daily behaviors and sleep-related quality of life among First Nations participants using the Functional Outcomes of Sleep Questionnaire (FOSQ-10). The First Nations Sleep Health Project follow-up survey was conducted in partnership with two Cree First Nations in the summer of 2022, where 355 individuals participated. Statistical analysis was conducted using logistic regression models. The mean age of the participants was 40.76 ± 14.60 (SD) years, and 59.4% were females. The prevalence of chronic insomnia (Insomnia Severity Index score of ≥15) was 21.0%, with more females (26.1%) than males (13.8%) experiencing it among the 348 participants. Overall, the mean FOSQ-10 score was 17.27 ± 2.98 among the 350 participants, with those who had clinical insomnia reporting significantly lower scores than those without clinical insomnia (mean ± SD: 14.6 ± 3.9 vs. 18.0 ± 2.1; p < 0.001). The FOSQ-10 scores indicated sleep-related functional impairment (FOSQ-10 total score < 17.90) in 46.6% of participants. After adjusting for age, excessive daytime sleepiness, sex, and regular use of prescription medication, we found that clinical insomnia was significantly associated with functional impairments. In fact, a person with clinical insomnia was 3.5 times more likely to have functional impairments than those without clinical insomnia. This study highlights the significant association between insomnia and functional impairments related to daily behaviors and quality of life in two First Nation communities. Identifying this association can help healthcare providers to diagnose and treat patients with insomnia in these communities.
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(This article belongs to the Section Disorders)
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Open AccessArticle
The Validation of the SOMNOwatch™ Actigraphy System for Periodic Limb Movements in Sleep Assessment
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Ekaterina Spektor, Ingo Fietze and Mikhail G. Poluektov
Clocks & Sleep 2024, 6(4), 568-577; https://doi.org/10.3390/clockssleep6040038 - 10 Oct 2024
Abstract
There is a growing body of evidence regarding the clinical significance of PLMS, and this movement disorder is of concern in both clinical and scientific contexts. Leg actigraphy is a convenient and promising method for screening periodic limb movements in sleep (PLMSs). This
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There is a growing body of evidence regarding the clinical significance of PLMS, and this movement disorder is of concern in both clinical and scientific contexts. Leg actigraphy is a convenient and promising method for screening periodic limb movements in sleep (PLMSs). This study aims to demonstrate the reliability of the SOMNOwatch™ actigraph for detecting periodic limb movements in sleep. Twenty-eight patients, referred to a sleep laboratory for various sleep problems, underwent nocturnal polysomnography with simultaneous one-sided actigraphy using the SOMNOwatch™ actigraph. Recordings of leg movements obtained from both methods were manually scored, calculating the periodic limb movement index (PLMI). The agreement between the methods was assessed through correlation analysis and event-by-event comparison. The correlation between the PLMI derived from PSG and SOMNOwatch™ was high and statistically significant (r = 0.98, p < 0.0001). The SOMNOwatch™ demonstrated a sensitivity of 86.7% and a specificity of 92.3% in detecting PLMS. Similarly, for detecting patients with a PLMI equal to or greater than 15, the sensitivity was 85.7%, and the specificity was 95.2%.
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(This article belongs to the Special Issue Sleeping for Health: Mechanistic Insights)
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A Longitudinal Examination between Chronotype and Insomnia in Youths: A Cross-Lagged Panel Analysis
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Forrest Tin Wai Cheung, Hao Fong Sit, Xiao Li, Joey Wing Yan Chan, Ngan Yin Chan, Yun Kwok Wing and Shirley Xin Li
Clocks & Sleep 2024, 6(4), 557-567; https://doi.org/10.3390/clockssleep6040037 - 10 Oct 2024
Abstract
Adolescence and young adulthood are transitional periods associated with significant changes and challenges, leading to a heightened vulnerability to sleep disturbances and mental health difficulties. This stage is often associated with an increased preference for eveningness, manifested as a later chronotype. The current
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Adolescence and young adulthood are transitional periods associated with significant changes and challenges, leading to a heightened vulnerability to sleep disturbances and mental health difficulties. This stage is often associated with an increased preference for eveningness, manifested as a later chronotype. The current study aimed to investigate the directionality of the association between chronotype, based on an individual’s sleep–wake behaviour, and insomnia in young people using a two-wave panel design with a 12-month interval. A total of 370 participants aged 15–24 (mean age: 21.0 ± 2.0, 72.7% female) were recruited from local secondary schools and universities. Insomnia symptoms were assessed using the Insomnia Severity Index, while chronotype was measured using the Munich Chronotype Questionnaire. Temporal associations were analysed using a series of cross-lagged panel models. The best fitting and most parsimonious model indicated that a later chronotype at baseline predicts more severe insomnia symptoms at the 12-month follow-up after accounting for autoregressive effects. However, the opposite causal model, where baseline insomnia symptoms predicted the chronotype at the 12-month follow-up, was not supported. These findings suggest that a late chronotype may be a potential risk factor for the development of insomnia in young people, emphasising the importance of considering circadian factors in the prevention and treatment of sleep disturbances among this population.
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(This article belongs to the Section Disorders)
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The Effect of Acute Sleep Extension on Blood Pressure Is Dependent on the Change in Sleep Efficiency
by
Joaquin U. Gonzales, Cayla Clark and Jacob R. Dellinger
Clocks & Sleep 2024, 6(4), 546-556; https://doi.org/10.3390/clockssleep6040036 - 4 Oct 2024
Abstract
The present study investigated the effect of acute sleep extension on blood pressure and microvascular vasodilation. Sleep and daily physical activity were objectively measured at home for two weeks using wrist actigraphy in 22 adults (60 ± 15 y). Vascular measurements were made
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The present study investigated the effect of acute sleep extension on blood pressure and microvascular vasodilation. Sleep and daily physical activity were objectively measured at home for two weeks using wrist actigraphy in 22 adults (60 ± 15 y). Vascular measurements were made in the morning on the 8th and 15th day. Participants spent at least 10 h in bed on the night prior to one of these testing days to extend sleep. Mean arterial blood pressure (MAP) and peak reactive hyperemia in the forearm were measured on each testing day. Reactive hyperemia and MAP were unaltered (p > 0.05) by sleep extension in the total sample. However, adults who experienced improved sleep efficiency with sleep extension (n = 10, 4.2 ± 1.4%) exhibited reduced MAP (−5.5 ± 4.6 mm Hg, p = 0.005) while adults who had little change or decreased sleep efficiency (n = 12, −1.7 ± 2.9%) showed no change in MAP. The reduction in MAP was significantly different between sleep efficiency groups (p = 0.005, Hedges’ g = 1.21) after adjustment for sex and moderate-to-vigorous physical activity. The results of this study suggest that sleep extension has the potential to reduce blood pressure in midlife to older adults when the additional sleep time improves the quality of sleep.
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(This article belongs to the Section Human Basic Research & Neuroimaging)
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Associations between Sleep Duration and Autonomic Nervous System Regulation in Patients with Probable Alzheimer’s Disease: A Cross-Sectional Pilot Study
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Chuen-Ru Liu, Chih-Yuan Yang, Dipanshu Sharma, Tun-Hao Chen, Xian-Qing Huang, Tsui-Mei Hung, Terry B. J. Kuo and Jwo-Huei Jou
Clocks & Sleep 2024, 6(4), 533-545; https://doi.org/10.3390/clockssleep6040035 - 24 Sep 2024
Abstract
In this study, we aimed to investigate the relationships between sleep duration and autonomic nervous system (ANS) regulation. This cross-sectional pilot study included 27 older patients with probable Alzheimer’s disease who were hospitalized at a psychiatric center. We measured heart rate variability to
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In this study, we aimed to investigate the relationships between sleep duration and autonomic nervous system (ANS) regulation. This cross-sectional pilot study included 27 older patients with probable Alzheimer’s disease who were hospitalized at a psychiatric center. We measured heart rate variability to assess ANS regulation at night, evaluated dementia severity via the Clinical Dementia Rating scale, and obtained sleep duration data from sleep diaries maintained by psychiatric nurses. The data were analyzed using repeated-measures generalized linear models with age, sex, dementia severity, hypertension status, and medication use (antipsychotics) as covariates. A sleep duration of 6–9 h per night compared to shorter than 6 h was associated with a greater increase in parasympathetic nervous system activity (p = 0.03), and a sleep duration longer than 9 h was associated with a decrease sympathovagal balance (p = 0.02). In addition, we observed an inverted U-shaped association between sleep duration and ANS regulation. In this pilot study, we demonstrated that a sleep duration of 6–9 h per night may be beneficial for ANS regulation; however, the present study involved only a few participants and had some limitations. Additional research with a larger cohort is needed to confirm these findings.
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(This article belongs to the Section Human Basic Research & Neuroimaging)
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Use of mHealth Technologies to Increase Sleep Quality among Older Adults: A Scoping Review
by
Giulia Grotto, Michela Martinello and Alessandra Buja
Clocks & Sleep 2024, 6(3), 517-532; https://doi.org/10.3390/clockssleep6030034 - 4 Sep 2024
Abstract
Sleep disorders increase with age and are known risk factors for several mental and physical diseases. They also significantly contribute to a lower quality of life. Nonpharmaceutical approaches, such as cognitive behavioral therapy for insomnia, sleep hygiene advice, relaxation exercises, and physical activity
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Sleep disorders increase with age and are known risk factors for several mental and physical diseases. They also significantly contribute to a lower quality of life. Nonpharmaceutical approaches, such as cognitive behavioral therapy for insomnia, sleep hygiene advice, relaxation exercises, and physical activity programs, can be delivered directly to patients via mHealth technologies, thereby increasing the accessibility of such interventions and reducing health care-related costs. This scoping review aims to evaluate the effectiveness of mHealth interventions for improving sleep quality among older adults. Published studies in the last 10 years (2013–2023) were identified by searching electronic medical databases (PubMed, PsycINFO, CINAHL, and Scopus) in July 2023 and were independently reviewed by two different authors. The analysis of the data was performed in 2023. The research retrieved 693 records; after duplicates were removed, 524 articles were screened based on their title and abstract, and 28 of them were assessed in full text. A total of 23 studies were excluded because they did not meet the inclusion criteria in terms of population age (60 years or over) or type of intervention (mHealth-based) or because they addressed secondary insomnia. A total of five studies were included in this review, and all of them reported improvements in subjective sleep quality after the application of the mHealth interventions. Two studies also conducted objective assessments of sleep outcomes using actigraphy, reporting improvements only in some of the variables considered. Despite the limited number of available studies, these results are promising and encourage further research.
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(This article belongs to the Section Human Basic Research & Neuroimaging)
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The Impact of DAZZEON αSleep® Far-Infrared Blanket on Sleep, Blood Pressure, Vascular Health, Muscle Function, Inflammation, and Fatigue
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Mon-Chien Lee, Chin-Shan Ho, Yi-Ju Hsu, Nai-Wen Kan, Chen-Yin Fei, Hung-Jen Yang and Chi-Chang Huang
Clocks & Sleep 2024, 6(3), 499-516; https://doi.org/10.3390/clockssleep6030033 - 4 Sep 2024
Abstract
The application of far-infrared blankets has shown certain benefits in health promotion and therapy, such as improving blood circulation and alleviating muscle pain. However, the effects of such blankets on increasing deep sleep, reducing blood pressure, enhancing memory, dilating microvessels for blood flow,
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The application of far-infrared blankets has shown certain benefits in health promotion and therapy, such as improving blood circulation and alleviating muscle pain. However, the effects of such blankets on increasing deep sleep, reducing blood pressure, enhancing memory, dilating microvessels for blood flow, reducing chronic inflammation, and decreasing fatigue remain to be studied. We aim to investigate the effects of the DAZZEON αSleep® far-infrared blanket on these indicators. This study adopted a double-blind design, recruiting 24 male participants aged over 45 years, divided into two groups of 12 each: (A) a placebo group and (B) a DAZZEON αSleep® group. The participants used the blanket every night for two weeks, with sleep records taken using a wearable device and blood pressure, blood oxygen levels, arterial stiffness, and surface temperature measured before and after the intervention. Blood samples were collected for an analysis of inflammation and sleep-related blood indicators (serotonin and melatonin), and exercise tests were conducted to assess fatigue improvement. Compared with before the intervention, the blanket significantly increased changes in grip strength and reaction time. Additionally, it significantly increased blood serotonin, melatonin, and nitric oxide concentrations (p < 0.05), thus significantly increasing deep sleep and REM sleep durations (p < 0.05) and improving subjective sleep quality (p < 0.05). This study confirmed that using the DAZZEON αSleep® far-infrared blanket for 14 consecutive days helps to improve blood circulation, reduce vascular age and arterial stiffness, increase serotonin and melatonin levels, and improve sleep quality, as well as enhances muscle strength and reaction time.
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(This article belongs to the Section Impact of Light & other Zeitgebers)
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Sleep Quality and Medication Adherence in Older Adults: A Systematic Review
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Leandro Amato, Noemi Giannetta, Sofia Taborri, Sara Dionisi, Nicolò Panattoni, Emanuele Di Simone, Aurora De Leo, Gloria Liquori, Giovanni Battista Orsi, Fabio Fabbian and Marco Di Muzio
Clocks & Sleep 2024, 6(3), 488-498; https://doi.org/10.3390/clockssleep6030032 - 3 Sep 2024
Abstract
Sleep quality significantly impacts individuals’ overall health, especially in older adults. Older adults often face comorbid conditions, polypharmacy (the intake of five or more medications per day), and medication non-adherence, which are common among those with sleep disorders. The purpose of this systematic
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Sleep quality significantly impacts individuals’ overall health, especially in older adults. Older adults often face comorbid conditions, polypharmacy (the intake of five or more medications per day), and medication non-adherence, which are common among those with sleep disorders. The purpose of this systematic review is to examine the relationship between sleep quality and medication adherence in older adults and to describe the measuring instruments used. A systematic review was performed following the PRISMA guidelines. The PubMed, Scopus, Cochrane Library, and CINAHL databases were screened from January 2024 to March 2024. Nine articles were included in the final synthesis based on the inclusion and exclusion criteria. The review found that poor sleep quality is significantly associated with reduced medication adherence in older adults. The key sleep determinants linked to medication non-adherence include sleep disorders, sleep efficiency, sleep duration, and daytime dysfunctions. Inappropriate medication prescriptions have been associated with reduced sleep efficiency. The tools for assessing sleep quality and medication adherence are predominantly subjective and varied. To address these challenges, a comprehensive geriatric assessment should include investigations into sleep disorders and comorbidity factors. Additionally, nursing educational interventions could be pivotal in improving medication adherence among older adults.
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(This article belongs to the Section Human Basic Research & Neuroimaging)
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A Comprehensive Assessment of Bedtime Routines and Strategies to Aid Sleep Onset in College Students: A Web-Based Survey
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Debora Meneo, Sara Curati, Paolo Maria Russo, Monica Martoni, Francesca Gelfo and Chiara Baglioni
Clocks & Sleep 2024, 6(3), 468-487; https://doi.org/10.3390/clockssleep6030031 - 29 Aug 2024
Abstract
College students often experience sleep–wake alterations. Different factors can contribute to insomnia symptoms in this population. The present study aims at investigating pre-sleep behaviours and strategies used to aid sleep onset in young college students and their association with insomnia symptoms. A total
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College students often experience sleep–wake alterations. Different factors can contribute to insomnia symptoms in this population. The present study aims at investigating pre-sleep behaviours and strategies used to aid sleep onset in young college students and their association with insomnia symptoms. A total of 548 Italian college students (mean age = 23.48 years, range = 19–30 years, 80.5% female) completed a web-based survey on pre-sleep behaviours and sleep-onset facilitators, insomnia symptoms and sleep hygiene, anxiety and depression, and coping strategies. The use of electronic devices at bedtime and as a sleep-onset facilitator was predominant. Students using specific behaviours as sleep-onset facilitators were characterised by more psychological difficulties and poorer sleep. In multivariable linear regression analysis, the frequency of using medications and melatonin, regardless of motivations, was associated with higher insomnia symptoms. The use of specific sleep-onset facilitators positively correlated with the severity of insomnia symptoms. Many students engage in behaviours that are considered sleep-interfering and that are often employed in an attempt to facilitate sleep onset without benefits. Overall, the motivational factors behind pre-sleep behaviours need to be addressed in preventive programs targeting young college students.
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(This article belongs to the Section Human Basic Research & Neuroimaging)
Open AccessReview
Disrupted Circadian Rhythms and Substance Use Disorders: A Narrative Review
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Pallavi Sharma and Randy J. Nelson
Clocks & Sleep 2024, 6(3), 446-467; https://doi.org/10.3390/clockssleep6030030 - 19 Aug 2024
Abstract
Substance use disorder is a major global health concern, with a high prevalence among adolescents and young adults. The most common substances of abuse include alcohol, marijuana, cocaine, nicotine, and opiates. Evidence suggests that a mismatch between contemporary lifestyle and environmental demands leads
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Substance use disorder is a major global health concern, with a high prevalence among adolescents and young adults. The most common substances of abuse include alcohol, marijuana, cocaine, nicotine, and opiates. Evidence suggests that a mismatch between contemporary lifestyle and environmental demands leads to disrupted circadian rhythms that impair optimal physiological and behavioral function, which can increase the vulnerability to develop substance use disorder and related problems. The circadian system plays an important role in regulating the sleep–wake cycle and reward processing, both of which directly affect substance abuse. Distorted substance use can have a reciprocal effect on the circadian system by influencing circadian clock gene expression. Considering the detrimental health consequences and profound societal impact of substance use disorder, it is crucial to comprehend its complex association with circadian rhythms, which can pave the way for the generation of novel chronotherapeutic treatment approaches. In this narrative review, we have explored the potential contributions of disrupted circadian rhythms and sleep on use and relapse of different substances of abuse. The involvement of circadian clock genes with drug reward pathways is discussed, along with the potential research areas that can be explored to minimize disordered substance use by improving circadian hygiene.
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(This article belongs to the Section Impact of Light & other Zeitgebers)
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Violet Light Effects on the Circadian Rest–Activity Rhythm and the Visual System
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Teresa Domínguez-Valdés, Cristina Bonnin-Arias, Cristina Alvarez-Peregrina, Beatriz G. Galvez, Miguel Angel Sanchez-Tena, Francisco Germain, Pedro de la Villa and Celia Sánchez-Ramos
Clocks & Sleep 2024, 6(3), 433-445; https://doi.org/10.3390/clockssleep6030029 - 14 Aug 2024
Abstract
Background: Rooms illuminated by “black light” (<400 nm wavelength) has become popular, but there is not enough scientific evidence to support its implementation. This study aims to assess the effects of violet light (392 nm) on the circadian rest–activity rhythm and the visual
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Background: Rooms illuminated by “black light” (<400 nm wavelength) has become popular, but there is not enough scientific evidence to support its implementation. This study aims to assess the effects of violet light (392 nm) on the circadian rest–activity rhythm and the visual system through animal experimentation. Materials and results: Five groups of four mice were exposed to different white light, violet light, and dark periods, and their circadian rhythm was analyzed by measuring the circadian period using rest–activity cycles. Electroretinographic recordings and structural analysis of the retina were also performed on experimental animals. Results: Our study demonstrates that mice present normal circadian activity during exposure to violet light, taking rest not only under white light but under violet lighting periods. However, mice suffered a decrease in electrical retinal response after exposure to violet light as measured by electroretinography. Nevertheless, no structural changes were observed in the retinas of the animals under different lighting conditions. Conclusions: Violet light elicits circadian rest–activity rhythm in mice but alters their visual function, although no structural changes are observed after short periods of violet light exposure.
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(This article belongs to the Section Impact of Light & other Zeitgebers)
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Effectiveness of Enriched Milk with Ashwagandha Extract and Tryptophan for Improving Subjective Sleep Quality in Adults with Sleep Problems: A Randomized Double-Blind Controlled Trial
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Silvia Pérez-Piñero, Juan Carlos Muñoz-Carrillo, Jon Echepare-Taberna, Macarena Muñoz-Cámara, Cristina Herrera-Fernández, Vicente Ávila-Gandía, María Heres Fernández Ladreda, Javier Menéndez Martínez and Francisco Javier López-Román
Clocks & Sleep 2024, 6(3), 417-432; https://doi.org/10.3390/clockssleep6030028 - 9 Aug 2024
Abstract
A randomized, double-blind and controlled study was conducted to assess the effectiveness of the intake of 250 mL of lactose-free skimmed milk enriched with ashwagandha (Withania somnifera) alone or combined with tryptophan vs. non-enriched milk (control) on the subjective quality of sleep
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A randomized, double-blind and controlled study was conducted to assess the effectiveness of the intake of 250 mL of lactose-free skimmed milk enriched with ashwagandha (Withania somnifera) alone or combined with tryptophan vs. non-enriched milk (control) on the subjective quality of sleep in healthy adults with sleep problems. The duration of supplementation was 90 days. Fifty-two eligible subjects were assigned to the study arms of ashwagandha 250 mg, ashwagandha 250 mg plus tryptophan 175 mg, ashwagandha 600 mg, and control with 13 subjects in each group. It was hypothesized that ashwagandha plus tryptophan could be superior to ashwagandha alone for improving sleep-related variables. Changes in the visual analogue scale (VAS) for sleep quality were significantly higher in the three experimental groups as compared with controls (p = 0.014). Improvements in the subscales of the Pittsburg Sleep Quality Index (PSQI) were found in all groups, but between-group differences were not significant. In the index of insomnia severity, decreases were higher in the three experimental groups as compared with controls especially in the group of ashwagandha 600 mg. Daytime somnolence was also reduced in the three experimental groups. Changes in anxiety levels and Morningness–Eveningness Questionnaire were not observed. The study products did not elicit changes in body composition and were well tolerated and safe. The data did not support the hypothesis, as the combination of ashwagandha and tryptophan did not show greater benefits in improving sleep quality than ashwagandha alone. However, the results from the three experimental groups containing ashwagandha were more favorable compared to the placebo group.
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(This article belongs to the Section Disorders)
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The Impact of Lunch Timing on Nap Quality
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Jennifer E. Fudge, Emily T. Peterson, Shae-Lynn M. Koe and Hans C. Dringenberg
Clocks & Sleep 2024, 6(3), 402-416; https://doi.org/10.3390/clockssleep6030027 - 5 Aug 2024
Abstract
Purpose: Previous research has established that food intake is a biological regulator of the human sleep–wake cycle. As such, the timing of eating relative to sleep may influence the quality of sleep, including daytime naps. Here, we examine whether the timing of lunch
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Purpose: Previous research has established that food intake is a biological regulator of the human sleep–wake cycle. As such, the timing of eating relative to sleep may influence the quality of sleep, including daytime naps. Here, we examine whether the timing of lunch (1 h vs. 2 h interval between lunch and a napping opportunity) impacts the quality of an afternoon nap. Methods: Using a randomized within-subject design over two separate experimental sessions (7 days apart), participants (n = 40, mean age = 25.8 years) consumed lunch 1 h and 2 h prior to an afternoon nap opportunity. Polysomnography and subjective self-reports were used to assess sleep architecture, sleepiness levels, and nap quality. Results: Results revealed no significant differences in subjective ratings of sleep quality and sleepiness, or in sleep architecture (total sleep time, sleep efficiency, sleep onset latency, sleep stages) between the 1 h and 2-h lunch conditions. Conclusions: All sleep measures were similar when napping followed eating by either 1 h or 2 h, suggesting that eating closer to nap onset may not negatively impact sleep architecture and quality. Future research should continue to identify conditions that improve nap quality, given the well-documented benefits of naps to reduce sleep pressure and improve human performance.
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(This article belongs to the Section Human Basic Research & Neuroimaging)
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Open AccessArticle
Risk of Comorbid Insomnia Disorder Associated with Major Depression in Apneic Patients: A Cross-Sectional Study
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Matthieu Hein, Benjamin Wacquier, Matteo Conenna, Jean-Pol Lanquart and Camille Point
Clocks & Sleep 2024, 6(3), 389-401; https://doi.org/10.3390/clockssleep6030026 - 26 Jul 2024
Cited by 1
Abstract
Given the limitations of available studies, the objective of this study was to explore the role played by current and remitted major depression in the occurrence of comorbid insomnia disorder for apneic patients. Data from 1488 apneic patients were extracted from the medical
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Given the limitations of available studies, the objective of this study was to explore the role played by current and remitted major depression in the occurrence of comorbid insomnia disorder for apneic patients. Data from 1488 apneic patients were extracted from the medical reports of polysomnographic recordings available in the database of the Sleep Laboratory. The presence of comorbid insomnia disorder in these apneic patients was defined based on the diagnostic criteria of the American Academy of Sleep Medicine Work Group. The risk of comorbid insomnia disorder associated with current or remitted major depression in apneic patients was investigated using multivariate logistic regression models. After adjustment for the main confounding factors, multivariate logistic regression analyses revealed that remitted and current major depression were significantly associated with the occurrence of comorbid insomnia disorder in apneic patients. The findings of this study seem to indicate that comorbid insomnia disorder could be a residual symptom and a marker of major depression in apneic patients, which justifies the establishment of an adequate treatment for major depressive episodes and their potential residual symptoms to allow the better management of comorbid insomnia disorder and the better prevention of its potential negative consequences in this particular subpopulation.
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(This article belongs to the Section Disorders)
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Generative Models for Periodicity Detection in Noisy Signals
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Ezekiel Barnett, Olga Kaiser, Jonathan Masci, Ernst C. Wit and Stephany Fulda
Clocks & Sleep 2024, 6(3), 359-388; https://doi.org/10.3390/clockssleep6030025 - 23 Jul 2024
Abstract
We present the Gaussian Mixture Periodicity Detection Algorithm (GMPDA), a novel method for detecting periodicity in the binary time series of event onsets. The GMPDA addresses the periodicity detection problem by inferring parameters of a generative model. We introduce two models, the Clock
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We present the Gaussian Mixture Periodicity Detection Algorithm (GMPDA), a novel method for detecting periodicity in the binary time series of event onsets. The GMPDA addresses the periodicity detection problem by inferring parameters of a generative model. We introduce two models, the Clock Model and the Random Walk Model, which describe distinct periodic phenomena and provide a comprehensive generative framework. The GMPDA demonstrates robust performance in test cases involving single and multiple periodicities, as well as varying noise levels. Additionally, we evaluate the GMPDA on real-world data from recorded leg movements during sleep, where it successfully identifies expected periodicities despite high noise levels. The primary contributions of this paper include the development of two new models for generating periodic event behavior and the GMPDA, which exhibits high accuracy in detecting multiple periodicities even in noisy environments.
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(This article belongs to the Section Computational Models)
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Combined Effects of Moderate Hypoxia and Sleep Restriction on Mental Workload
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Anaïs Pontiggia, Pierre Fabries, Vincent Beauchamps, Michael Quiquempoix, Olivier Nespoulous, Clémentine Jacques, Mathias Guillard, Pascal Van Beers, Haïk Ayounts, Nathalie Koulmann, Danielle Gomez-Merino, Mounir Chennaoui and Fabien Sauvet
Clocks & Sleep 2024, 6(3), 338-358; https://doi.org/10.3390/clockssleep6030024 - 23 Jul 2024
Abstract
Aircraft pilots face a high mental workload (MW) under environmental constraints induced by high altitude and sometimes sleep restriction (SR). Our aim was to assess the combined effects of hypoxia and sleep restriction on cognitive and physiological responses to different MW levels using
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Aircraft pilots face a high mental workload (MW) under environmental constraints induced by high altitude and sometimes sleep restriction (SR). Our aim was to assess the combined effects of hypoxia and sleep restriction on cognitive and physiological responses to different MW levels using the Multi-Attribute Test Battery (MATB)-II with an additional auditory Oddball-like task. Seventeen healthy subjects were subjected in random order to three 12-min periods of increased MW level (low, medium, and high): sleep restriction (SR, <3 h of total sleep time (TST)) vs. habitual sleep (HS, >6 h TST), hypoxia (HY, 2 h, FIO2 = 13.6%, ~3500 m vs. normoxia, NO, FIO2 = 21%). Following each MW level, participants completed the NASA-TLX subjective MW scale. Increasing MW decreases performance on the MATB-II Tracking task (p = 0.001, MW difficulty main effect) and increases NASA-TLX (p = 0.001). In the combined HY/SR condition, MATB-II performance was lower, and the NASA-TLX score was higher compared with the NO/HS condition, while no effect of hypoxia alone was observed. In the accuracy of the auditory task, there is a significant interaction between hypoxia and MW difficulty (F(2–176) = 3.14, p = 0.04), with lower values at high MW under hypoxic conditions. Breathing rate, pupil size, and amplitude of pupil dilation response (PDR) to auditory stimuli are associated with increased MW. These parameters are the best predictors of increased MW, independently of physiological constraints. Adding ECG, SpO2, or electrodermal conductance does not improve model performance. In conclusion, hypoxia and sleep restriction have an additive effect on MW. Physiological and electrophysiological responses must be taken into account when designing a MW predictive model and cross-validation.
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(This article belongs to the Section Human Basic Research & Neuroimaging)
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Predicting Sleep Quality through Biofeedback: A Machine Learning Approach Using Heart Rate Variability and Skin Temperature
by
Andrea Di Credico, David Perpetuini, Pascal Izzicupo, Giulia Gaggi, Nicola Mammarella, Alberto Di Domenico, Rocco Palumbo, Pasquale La Malva, Daniela Cardone, Arcangelo Merla, Barbara Ghinassi and Angela Di Baldassarre
Clocks & Sleep 2024, 6(3), 322-337; https://doi.org/10.3390/clockssleep6030023 - 23 Jul 2024
Abstract
Sleep quality (SQ) is a crucial aspect of overall health. Poor sleep quality may cause cognitive impairment, mood disturbances, and an increased risk of chronic diseases. Therefore, assessing sleep quality helps identify individuals at risk and develop effective interventions. SQ has been demonstrated
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Sleep quality (SQ) is a crucial aspect of overall health. Poor sleep quality may cause cognitive impairment, mood disturbances, and an increased risk of chronic diseases. Therefore, assessing sleep quality helps identify individuals at risk and develop effective interventions. SQ has been demonstrated to affect heart rate variability (HRV) and skin temperature even during wakefulness. In this perspective, using wearables and contactless technologies to continuously monitor HR and skin temperature is highly suited for assessing objective SQ. However, studies modeling the relationship linking HRV and skin temperature metrics evaluated during wakefulness to predict SQ are lacking. This study aims to develop machine learning models based on HRV and skin temperature that estimate SQ as assessed by the Pittsburgh Sleep Quality Index (PSQI). HRV was measured with a wearable sensor, and facial skin temperature was measured by infrared thermal imaging. Classification models based on unimodal and multimodal HRV and skin temperature were developed. A Support Vector Machine applied to multimodal HRV and skin temperature delivered the best classification accuracy, 83.4%. This study can pave the way for the employment of wearable and contactless technologies to monitor SQ for ergonomic applications. The proposed method significantly advances the field by achieving a higher classification accuracy than existing state-of-the-art methods. Our multimodal approach leverages the synergistic effects of HRV and skin temperature metrics, thus providing a more comprehensive assessment of SQ. Quantitative performance indicators, such as the 83.4% classification accuracy, underscore the robustness and potential of our method in accurately predicting sleep quality using non-intrusive measurements taken during wakefulness.
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(This article belongs to the Section Computational Models)
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