The cumulative bridge: how long-term physical activity and social engagement gradually enhance sleep health in aging adults

BACKGROUND AND OBJECTIVES: Sleep disturbances are significant public health issues for middle-aged and older adults. While cross-sectional research shows associations, a comprehensive understanding of the long-term, cumulative dynamics among multiple health behaviours and sleep duration remains underdeveloped. This study examines the distinct temporal effects and synergistic potential of sustained physical activity and social engagement on sleep duration in the ageing population. RESEARCH METHODOLOGY: Using five waves of longitudinal panel data from the China Health and Retirement Longitudinal Study (CHARLS, 2011–2018), we analysed 5,082 participants (57,716 observations). We employed a nested fixed-effects model with interactions between behaviours and time (survey wave) to control for individual unobservable heterogeneity and capture dynamic effects. Control variables included marital status, gender, age, education level, drinking habits, and chronic diseases. RESULTS: The direct effect of physical activity on sleep duration was negative in the short term. Crucially, its interaction with time showed a significant positive cumulative effect. Social activity also demonstrated a positive temporal effect, though the magnitude was notably smaller. Marital status exhibited a significant protective effect, and drinking habits were significantly negative. The temporal beneficial impact of physical activity was most pronounced in the middle school education group. CONCLUSIONS​: Long-term engagement in both physical activity and social activities positively enhances sleep duration, with physical activity having a more substantial and long-lasting protective impact that accrues over time. These findings underscore the need for public health policies to emphasise sustained, long-term interventions and consider education-level heterogeneity to maximise sleep benefits for ageing adults.