Gender differences in nighttime sleep patterns and variability across the adult lifespan: a global-scale wearables study.
Level 3 - non-randomized controlled study
Large observational cohort study using objective wearable tracker data across multiple countries.
PubMed 32886772 · doi:10.1093/sleep/zsaa169
What was done
Researchers analyzed 11.14 million nights of sleep recorded by consumer wearable activity trackers from 69,650 adult non-shift workers aged 19 to 67 across 47 countries. Mixed-effects models were used to evaluate age-related trajectories in sleep duration, timing, offset, and variability across genders and body mass index categories while controlling for individual- and country-level variation.
What was found
Across the lifespan, sleep duration decreased, nighttime awakenings increased, and sleep onset and offset times advanced earlier with age. Men generally slept less than women, but women had a higher prevalence of nighttime awakenings, with the largest gender disparity occurring during early-to-middle adulthood. Sleep onset and duration variability remained relatively constant across age but were higher on weekends than weekdays. Sleep offset variability dropped until ages 35–39, then plateaued on weekdays while continuing to fall on weekends. Specific numerical effect sizes (e.g., minutes of sleep lost or awakening counts) were not reported in the abstract.
Why it matters
This study provides large-scale, objective cross-national confirmation of age- and sex-dependent sleep architecture changes outside of artificial laboratory environments, highlighting life-stage-specific differences such as heightened awakenings in women during child-rearing years.
Limits
The abstract reports no exact numerical effect sizes or confidence intervals. The sample is restricted to non-shift workers who own specific consumer wearable devices, introducing potential socioeconomic and healthy-user selection biases. Wearable tracker algorithms also have inherent measurement errors relative to polysomnography.