Depressive symptoms and sleep duration in a mutual loop: a five-wave study of nationally representative Chinese couples

Background: Previous research has examined the bidirectional relations between sleep duration and depressive symptoms at the individual level. However, there is a scarcity of research on these potential transactional dynamics within couples, particularly distinguishing between- and within-couple effects. This longitudinal study aims to address these issues among middle-aged to older couples. Methods: We analyzed nationally representative data (N = 3809 couples) from the China Health and Retirement Longitudinal Study initiated in 2011, spanning over a decade. Mean ages of husbands and wives at first wave were 57.9 (SD = 7.98) and 55.9 (SD = 7.47), respectively. Husbands and wives independently reported their sleep duration and depressive symptoms at five timepoints. We applied Cross-Lagged Panel Model (CLPM) and Random Intercept (RI)-CLPM to disentangle between-couple and within-couple effects, examining the potential reciprocity between sleep duration and depressive symptoms. Results: The between-couple findings revealed positive associations in depressive symptoms and sleep duration within partners, along with bidirectional inverse associations between each individuals' depressive symptoms and their own sleep duration. However, no cross-domain associations were found between one partner's depressive symptoms and the other's sleep duration, or vice versa. The within-couple findings showed negative links between wives' sleep duration and their spouses' sleep duration, as well as positive links between wives' sleep duration and their spouses' depressive symptoms. Conclusions: This study underscores the intricate and multifaceted interplay between depressive symptoms and sleep duration, both within and between partners, and between and within couples.