Depressive symptoms among middle-aged and older adults in China: The interaction of physical activity and sleep duration

Background: Previous research on the interaction of physical activity and sleep on depressive symptoms was mostly cross-sectional or conducted with children or young adults. This study examines the main and interactive associations of physical activity and sleep duration with depressive symptoms over a 3-year period among middle-aged and older Chinese adults.

Methods: Data from 4269 Chinese adults aged 45 or older from the China Health and Retirement Longitudinal Study (CHARLS) were used. Physical activity was categorized as inadequate (<600 MET), adequate (600-8000 MET), and extremely high (>8000 MET). Sleep was classified as inadequate (<6 hours), adequate (6-9 hours), and excessive (>9 hours). The Center for Epidemiologic Studies Depression Scale (CES-D) was used to measure depressive symptoms.

Results: Inadequate sleep was linked to greater increases in depressive symptoms over 3years. A significant interaction between baseline physical activity and sleep duration in predicting depressive symptoms at the 3-year follow-up showed that inadequate sleep, when combined with either inadequate or extremely high physical activity, was associated with higher depressive symptoms at the 3-year follow-up. In middle-aged subgroups, for people with either inadequate physical activity or an extremely high level of physical activity, inadequate sleep was associated with higher CES-D score compared to adequate sleep; for older adults, only inadequate sleep was associated with a higher follow-up CES-D score.

Conclusion: Physical activity and sleep interactively impacted depressive symptoms, suggesting future personalized interventions that simultaneously target physical activity and sleep. Adequate sleep was associated with lower levels of future depressive symptoms in people with inadequate or extremely high physical activity.