Variations in sleep duration and timing: Weekday and seasonal variations in sleep are common in an analysis of 73 million nights from an objective sleep tracker

Abstract

Study Objectives

Irregular sleep is a major risk factor for adverse health. In a global sample with technology-enabled long-term objective sleep data spanning 3.5 years, we investigated variability in sleep duration and timing over weekdays, months, seasons, and years.

Methods

Registered users of an FDA-approved under-mattress sleep sensor who had ≥28 nights of sleep recordings and averaged ≥4 nights per/week between January 2020 and September 2023 were included for analyses. Generalized non-linear mixed models were used to assess associations between sleep duration and sleep timing with weekday, month, season, and year. Sub-group analyses were conducted by age, sex, and location.

Results

Data from 116,879 adults (90,333 males, 26,546 females) aged 49±14 years were analysed. Weekday variation was observed, with 20-35 mins longer sleep duration on weekends vs. weekdays. Time to bed and time out of bed were 30-40 mins and 60-80 mins later on weekends, respectively. Seasonal variation in sleep duration was also evident; sleep duration was 15-20 mins longer during winter in the northern hemisphere, 15-20 mins shorter during summer in the southern hemisphere, and variations reduced closer to the equator. Sleep duration decreased from 2020-2023 but the effect was small (2.5min).

Conclusions

These novel findings underscore the seasonal nature of human sleep, influenced by demographics and geography.

Graphical Abstract

big data, aging, sleep technology, sleep health, sleep duration, sleep timing, sleep variability, sleep regularity

Accepted manuscripts

Accepted manuscripts are PDF versions of the author’s final manuscript, as accepted for publication by the journal but prior to copyediting or typesetting. They can be cited using the author(s), article title, journal title, year of online publication, and DOI. They will be replaced by the final typeset articles, which may therefore contain changes. The DOI will remain the same throughout.

Author notes

Hannah Scott and Bastien Lechat Contributed equally