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:

• Objective sleep measurement is crucial for understanding age-related sleep changes.
• Wearable technology offers large-scale data collection for sleep research.

Purpose of the Study:

• To investigate the association between age and objectively measured sleep parameters in women.
• To compare age-related sleep patterns between women and men.

Main Methods:

• Analysis of approximately 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 were adjusted for country, BMI, weekday/weekend, and daily activity time, with separate analyses for men.

Main Results:

• Women aged 50-64 years showed notable increases in WASO, with average increases of up to 11 minutes (32%) compared to younger women.
• Age-related decreases in TSPD and TST were modest (≤17 minutes).
• Sleep patterns varied by country, with shorter TSPD and TST in South Korea and earlier WASO increases.

Conclusions:

• Midlife is associated with a pronounced increase in wakefulness after sleep onset among women.
• Targeted interventions for sleep improvement in midlife women are recommended as part of health counseling.
• Understanding age-specific sleep changes is vital for promoting women's health.