Wife-husband differences in the associations between sleep durations and global cognition among middle-aged and older married couples in China: a longitudinal dyadic analysis.

Abstract

Background: Sleep duration has well-established U-shaped associations with cognitive health, but research has largely ignored spousal interdependence. This study examined actor and partner effects of sleep duration on global cognition in middle-aged and older Chinese couples, testing whether associations differed by sex.

Methods: Data were drawn from CHARLS waves 1-4 (2011-2018). The analytical sample comprised 4260 couples (8520 individuals) aged ≥45 years living in a married, 2-person, mixed-sex household. Global cognition was assessed with a composite battery adapted from the Telephone Interview for Cognitive Status and Chinese Mini-Mental State Examination; nocturnal sleep and napping durations were self-reported. Actor-Partner Interdependence Models with quadratic terms examined actor effects (own sleep predicting own cognition) and partner effects (own sleep predicting spouse's cognition), with false discovery rate (FDR)-adjusted q-values and sex-equality tests.

Results: Significant inverted U-shaped actor effects were found for wives (β = -0.010, 95% CI: -0.014, -0.005, p < .001) and husbands (β = -0.011, 95% CI: -0.016, -0.006, p < .001); both survived FDR correction (q = 0.002, q < 0.001). Husbands' sleep was nominally associated with wives' cognition similarly (β = -0.005, p = .025), while wives' sleep was not associated with husbands' cognition (p = .618). The husband-to-wife association did not survive FDR correction (q = 0.239), and sex-equality tests were non-significant (χ²(9) = 9.35, p = .406). Napping showed limited, largely non-significant associations with cognition.

Conclusions: Own nocturnal sleep duration shows a robust, symmetric inverted U-shaped association with cognitive function in both spouses. The possible husband-to-wife partner effect did not survive correction for multiple testing and warrants adequately powered investigation before informing couple-based clinical recommendations.