Sleep Duration and Risk of Depression: Empirical Evidence from Chinese Middle-Aged and Older Adults

Objective: To investigate the relationships between sleep duration and depression among middle-aged and older adults in China. Methods: This study used the data of 17,744 respondents from the 2018 China Health and Retirement Longitudinal Study (CHARLS), an ongoing national longitudinal survey of Chinese adults aged 45 years and above. Self-reported sleep duration per night was obtained from face-to-face interviews. Depression was evaluated using the 10-item Center for Epidemiological Studies-Depression scale (CES-D 10). The multivariable generalized linear model (GLM) was adopted to estimate the associations between sleep duration and depression. Results: Of the 17,744 respondents, 8425 (47.5%) were men. The mean (SD) age was 62.6 (10.0) years old. Respondents with short (≤4, 5 h per night) sleep duration had a higher risk of depression [odds ratio (OR): 2.77, 95% confidence interval (CI): 2.35–3.27), p < 0.001; OR: 1.65, 95% CI: 1.38–1.98, p < 0.001] compared with those slept for 7 h per night after adjusting for covariates. Long sleep duration (8, 9, ≥10) had no significant risk for depression. Restricted cubic splines analysis suggested that when sleep duration fell below 9 h, increased sleep duration was associated with a significantly lower risk of depression (OR: 0.82, 95% CI: 0.79–0.84, p < 0.001). When sleep duration exceeded 9 h, the risk of depression (OR: 1.03, 95% CI: 0.94–1.14, p = 0.512) would not increase significantly facing prolonged sleep duration. Conclusions: Short sleep duration was associated with depressive symptoms among middle-aged and older adults in China. Future studies are needed to focus on examining the cause-effect relationship between sleep duration and depression.