*3.3. Inclusion and Exclusion Criteria*

Participants were eligible for the study if they were over 18 years old, had access to an iPhone, had basic knowledge of installing and using mobile applications and wearable devices, and were willing and able to provide written informed consent and participate in study procedures. Participants were ineligible for the study if they were colorblind, part of a vulnerable population, or unwilling to consent and participate in study activities.

#### *3.4. Onboarding Questionnaires*

During the initial study visit, participants were prompted to complete four questionnaires (see Supplemental S1–S4). All questionnaires were completed electronically via SurveyMonkey and the results were subsequently stored in the study team's encrypted and secured electronic database.

The Demographics Questionnaire (Supplemental S1) ascertained basic demographic information.

The 36-Item Short Form Health Survey (SF-36; Supplemental S2). The SF-36 evaluated eight domains: physical functioning, role limitations due to physical health, role limitations due to emotional problems, energy/fatigue, emotional well-being, social functioning, pain, and general health. The SF-36 takes roughly 5–10 min to complete.

The Morningness-Eveningness Questionnaire (MEQ; Supplemental S3) is a 19-question, multiple-choice instrument designed to detect when a person's circadian rhythm allows for peak alertness. The MEQ takes roughly 5–10 min to complete.

The Pittsburgh Sleep Quality Instrument (PSQI; Supplemental S4) is a nine-item, self-rated questionnaire that assesses sleep over the prior month. The PSQI has been shown to be sensitive and specific in distinguishing between good and poor sleepers. The PSQI utilizes higher numbers to indicate poorer sleep. The PSQI takes roughly 5–10 min to complete.

#### *3.5. Technology Setup and Testing*

After the initial screening visit, participants were asked to set up their devices and begin the week-long study at their leisure (Figure 1). The study team chose technologies based on performance and usability data obtained from HS#: 15-00292, "Pilot Evaluation Study on Emerging Wearable Technologies." Each participant was assigned four sleep monitoring devices: a Fitbit Surge smart watch (Fitbit; first edition), a Hexoskin smart shirt (Hexoskin; male and female shirts and Classic device), a Withings Aura sleep pad/system (Withings; model number WAS01), and an Oura smart ring (Oura; first edition). Note that the form factors for the four devices were different; this was important to ensure that they could all be used at once and would not interfere with each other.

Setup for each device involved downloading the corresponding manufacturer's mobile application on the participant's iPhone and downloading the study team's custom HC App. Participants agreed to each manufacturer's software terms and conditions in the same manner as if they were to purchase and install the technologies themselves. In doing so, and as noted in the participant-signed consent document, participants acknowledged that the manufacturers would have access to identifiable information such as their names, email addresses, and locations. The HC App functioned as a portal to allow participants to authorize the sharing of data between the manufacturers' applications and the study team's database. During the initial setup period, the study team worked with participants to troubleshoot any issues and ensure proper data transmission to the database.

#### *3.6. Sleep Monitoring and Device-Specific Parameters*

Over a 7-day consecutive monitoring period of the participant's choosing, participants used the four different sleep monitoring technologies and completed daily assessments (Figure 1). The monitors measured physiological parameters (e.g., heart rate, heart rate variability, respiratory rate, temperature, and movement), activity parameters (e.g., number of steps per day), and sleep-related parameters, specifically time in each sleep stage, time in bed to fall asleep (latency), TSD, number of wakeups per night (wakeups), and standardized score of sleep quality (efficiency). The Withings and Oura both stage sleep as: (1) awake, (2) light, (3) deep, and (4) rapid eye movement (REM; Figure 1). The Hexoskin stages sleep as (1) awake, (2) non-REM (NREM), and (3) REM. The Fitbit stages sleep as (1) very awake, (2) awake, and (3) asleep.
