Abstract Introduction Sleep disturbances are common among midlife women. Wearables offer a novel, scalable approach to study sleep globally. Using Samsung Galaxy Watch data, we examined associations of age, weekdays/weekends, physical activity, and country with sleep parameters in an international cohort of women. Methods We analyzed sleep data from 192,500 women (aged 20–65 years) from France, Germany, South Korea, the UK, and the US (n=38,500/country). Sleep parameters included total sleep period duration (TSPD), total sleep time (TST), and wake after sleep onset (WASO; log-transformed). Linear mixed models assessed associations with age, weekdays/weekends, physical activity, and country (reference: US). An exploratory model included age-by-country interactions. Results Mean (standard deviation) values were: TSPD 439.4 (92.0) minutes, TST 391.2 (81.9) minutes, and WASO 48.3 (33.5) minutes. Age distributions were comparable across countries, with ~1/3 of women aged ≥50 years. Weekend nights were associated with ~24 minutes longer TSPD (+5.4%). Age and physical activity effects were small (±5 minutes). Women in South Korea had the shortest TSPD, averaging 27 minutes less (−6.2%) than US women. TST declined with age, with women aged ≥50 sleeping 13–17 minutes less (−3.3% to −4.4%) than those aged 20–24. Weekend nights were associated with ~21 minutes longer TST (+5.3%) than weeknights. Activity-related differences were small ( 3 minutes; 1%). Women in South Korea averaged a 25-minute shorter TST (−6.3%) versus US women. WASO increased with age; women aged ≥50 had 5–11 minutes more wakefulness (+15–32%) than those aged 20–24. Effects were small for weekend (+2 minutes; +5.4%), activity ( 1 minutes; −1.1% to −2.5%) and country (UK: +1.5 minutes; South Korea: −1 minute versus US). Age-related WASO increases were consistent across countries, except South Korea where interaction effects were greater. Conclusion Results demonstrated country-specific differences in TST and TSPD and age-related effects on TST and WASO, with differences evident in women aged ≥50, consistent with the menopausal transition. Smartwatch data provides large-scale sleep research potential to understand unique factors influencing sleep in women. Support (if any) Sponsored by Bayer and Samsung Electronics America. Medical writing assistance (Highfield, Oxford, UK) funded by Bayer.
Soares et al. (Fri,) studied this question.