The independent and combined associations of nocturnal sleep duration, sleep midpoint, and sleep onset latency with global cognitive function in older Chinese adults.

This study aims to investigate the independent and combined associations of nocturnal sleep duration, sleep midpoint, and sleep onset latency with global cognitive function in older Chinese adults. Our cross-sectional study included 4601 community-dwelling cognitively unimpaired adults aged 60 years or older from the West China Health and Aging Cohort Study. Sleep characteristics were assessed using the Pittsburgh Sleep Quality Index, and global cognitive function was evaluated using the Mini-Mental State Examination (MMSE). Multivariable linear regression models were employed, adjusting for an extensive set of demographic, lifestyle, and comorbidity factors. Subgroup analyses were performed based on sex, age, and genetic risk profiles for cognitive performance. The mean age of participants was 69.0 ± 5.53 years, with 52.1% being female. The mean MMSE total score was 24.9 ± 3.20. Compared to the reference category for each sleep variable, sleep duration < 5 h/day or > 8 h/day, sleep midpoint earlier than 1:30 AM, and sleep latency > 60 min were each independently associated with significantly lower MMSE scores (β range - 0.36 to - 0.34; 95% confidence interval range - 0.60 to - 0.10). A combined analysis revealed that individuals with concurrent extreme sleep duration, early midpoint, and/or long latency had even lower MMSE scores, especially among those with genetically predicted poorer cognitive performance (β up to - 1.86). Multiple dimensions of sleep are independently and jointly associated with global cognitive function in older Chinese adults, highlighting the importance of a holistic approach to sleep in cognitive aging research and interventions.