Sleep Pattern Differences in Women at Midlife: A Large-Scale Multi-Country Smartwatch Study (SONAR)

Area of Science:

• Sleep Science
• Gerontology
• Women's Health

Background:

• Age-related sleep changes are common but vary by sex.
• Objective sleep measurement provides valuable insights into population sleep patterns.

Purpose of the Study:

• To investigate the association between aging and objectively measured sleep parameters in women.
• To compare age-related sleep changes in women with those in men.

Main Methods:

• Analysis of ~3.8 million nights of sleep data from 192,500 female Galaxy Smartwatch users aged 20-65 years.
• Linear mixed models were used to assess associations between age and total sleep period duration (TSPD), total sleep time (TST), and wakefulness after sleep onset (WASO).
• Models adjusted for country, BMI, weekday/weekend, and daily activity, with age 20-24 as the reference group.

Main Results:

• Women showed a notable increase in WASO at midlife, with significant rises from age 50 onwards compared to the reference group.
• Age-related decreases in TSPD and TST were relatively small (≤17 minutes).
• Sleep patterns differed in South Korea, with shorter TSPD and TST across all ages and earlier increases in WASO.

Conclusions:

• Midlife is associated with a pronounced increase in wakefulness after sleep onset among women.
• Identifying and intervening early to improve sleep in midlife women is crucial for overall health.
• Tailored sleep interventions should be considered as part of health counseling for women approaching midlife.