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STUDY OBJECTIVES: The purpose of this study was to determine whether a wearable sleep-tracker improves perceived sleep quality in healthy participants and to test whether wearables reliably measure sleep quantity and quality compared with polysomnography. METHODS: This study included a single-center randomized crossover trial of community-based participants without medical conditions or sleep disorders. A wearable device (WHOOP, Inc.) was used that provided feedback regarding sleep information to the participant for 1 week and maintained sleep logs versus 1 week of maintained sleep logs alone. Self-reported daily sleep behaviors were documented in sleep logs. Polysomnography was performed on 1 night when wearing the wearable. The Patient-Reported Outcomes Measurement Information System sleep disturbance sleep scale was measured at baseline, day 7 and day 14 of study participation. RESULTS: In 32 participants (21 women; 23.8 ± 5 years), wearables improved nighttime sleep quality (Patient-Reported Outcomes Measurement Information System sleep disturbance: B = −1.69; 95% confidence interval, −3.11 to −0.27; P = .021) after adjusting for age, sex, baseline, and order effect. There was a small increase in self-reported daytime naps when wearing the device (B = 3.2; SE, 1.4; P = .023), but total daily sleep remained unchanged (P = .43). The wearable had low bias (13.8 minutes) and precision (17.8 minutes) errors for measuring sleep duration and measured dream sleep and slow wave sleep accurately (intraclass coefficient, 0.74 ± 0.28 and 0.85 ± 0.15, respectively). Bias and precision error for heart rate (bias, −0.17%; precision, 1.5%) and respiratory rate (bias, 1.8%; precision, 6.7%) were very low compared with that measured by electrocardiogram and inductance plethysmography during polysomnography. CONCLUSIONS: In healthy people, wearables can improve sleep quality and accurately measure sleep and cardiorespiratory variables. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: Assessment of Sleep by WHOOP in Ambulatory Subjects; Identifier: NCT03692195. CITATION: Berryhill S, Morton CJ, Dean A, et al. Effect of wearables on sleep in health individuals: a randomized crossover trial and validation study. J Clin Sleep Med. 2020;16(5):775–783.

STUDY OBJECTIVES: Studies have shown racial differences in circadian rhythm in African Americans when compared to non-Hispanic whites, and an association between circadian dyssynchrony and depression. We hypothesized that the prevalence of delayed sleep time is greater in African Americans when compared to whites and that delayed sleep time is associated with depression. METHODS: We analyzed data from the Sleep Heart Health Study (SHHS), a large community-based sample. Delayed sleep time was defined as self-reported weeknight bedtime after midnight. Depression was defined based on participant's response to the question, “In the past 4 weeks have you felt downhearted and blue?” or reported antidepressant use. We performed multivariate linear and logistic regression, adjusting for age, sex, race, body mass index, smoking, apnea-hypopnea index, alcohol use, and caffeine consumption. RESULTS: Adjusted weekday bedtime was 15 ± 7 minutes later in African Americans compared to whites (P < .001). Similarly, weekend bedtime was 18 ± 7 minutes later in African Americans compared to whites (P = .025). The prevalence of delayed sleep time was greater in African Americans (33.3%) compared to whites (18.7%; P < .001). After adjusting for confounders, when compared to whites, a greater proportion of African Americans had delayed sleep time (adjusted odds ratio [aOR] 2.03; 95% confidence interval [95% CI] 1.5, 2.4; P < .0001). Depression was independently associated with delayed sleep time after adjustment (aOR 1.4; 95% CI 1.1, 1.7; P = .007). CONCLUSIONS: African Americans are more likely to have a delayed sleep time compared to whites, and delayed sleep time was independently associated with depression. CITATION: Bailey O, Combs D, Sans-Fuentes M, Havens CM, Grandner MA, Poongkunran C, Patel S, Berryhill S, Provencio N, Quan SF, Parthasarathy S. Delayed sleep time in African Americans and depression in a community-based population. J Clin Sleep Med. 2019;15(6):857–864.

Introduction To determine whether a wearable sleep-tracker improves perceived sleep quality in healthy subjects. To test whether wearables reliably measure sleep quantity and quality compared to polysomnography. Methods A single-center randomized cross-over trial of community-based participants without medical conditions or sleep disorders. Wearable device (WHOOP, Inc.) that provided feedback regarding sleep information to the participant for 1-week and maintaining sleep logs versus 1-week of maintaining sleep logs alone. Self-reported daily sleep behaviors were documented in sleep logs. Polysomnography was performed on one night when wearing the wearable. PROMIS Sleep disturbance sleep scale was measured at baseline, 7, and 14 days of study participation. Results In 32 participants (21 women; 23.8 + 5 years), wearables improved nighttime sleep quality (PROMIS sleep disturbance; B= -1.69; 95% Confidence Interval -3.11, -0.27; P=0.021) after adjusting for age, sex, baseline, and order effect. There was a small increase in self-reported daytime naps when wearing the device (B = 3.2; SE 1.4; P=0.023) but total daily sleep remained unchanged (P=0.43). The wearable had low bias (2.5 minutes) and low precision (5.6 minutes) errors for measuring sleep duration and measured dream sleep and slow wave sleep accurately (Intra-class coefficient 0.74 + 0.28 and 0.85 + 0.15, respectively). Bias and precision error for heart rate (bias -0.17%; precision 1.5%) and respiratory rate (bias 1.8%’ precision 6.7%) were very low when compared to that measured by electrocardiogram and inductance plethysmography during polysomnography. Conclusion In healthy people, wearables can improve sleep quality and accurately measure sleep and cardiorespiratory variables. Support WHOOP Inc.

STUDY OBJECTIVES Prolonged exposure to blue wavelength light has been shown to have an alerting effect, and enhances performance on cognitive tasks. A small number of studies have also shown that relatively short exposure to blue light leads to changes in functional brain responses during the period of exposure. The extent to which blue light continues to affect brain functioning during a cognitively challenging task after cessation of longer periods of exposure (i.e., roughly 30 minutes or longer), however, has not been fully investigated. METHODS A total of 35 healthy participants (18 female) were exposed to either blue (469 nm) (n = 17) or amber (578 nm) (n = 18) wavelength light for 30 minutes in a darkened room, followed immediately by functional magnetic resonance imaging (fMRI) while undergoing a working memory task (N-back task). RESULTS Participants in the blue light condition were faster in their responses on the N-back task and showed increased activation in the dorsolateral (DLPFC) and ventrolateral (VLPFC) prefrontal cortex compared to those in the amber control light condition. Furthermore, greater activation within the VLPFC was correlated with faster N-back response times. CONCLUSIONS This is the first study to suggest that a relatively brief, single exposure to blue light has a subsequent beneficial effect on working memory performance, even after cessation of exposure, and leads to temporarily persisting functional brain changes within prefrontal brain regions associated with executive functions. These findings may have broader implication for using blue-enriched light in a variety of work settings where alertness and quick decision-making are important.