Sleep duration and depressive symptoms among older Chinese adults: a serial mediation model of self-rated health and frailty

Depressive symptoms in older adults compromise physical and mental health, burdening individuals, families, and society. Sleep duration, self-rated health (SRH), and frailty are critical correlates. Sleep shapes older adults’ health evaluation, and poor SRH elevates frailty risk. However, the interconnections among these four variables are rarely explored. Therefore, this study aimed to examine the serial mediating effect of SRH and frailty in the relationship between sleep duration and depressive symptoms in older adults.

We performed a cross-sectional study utilizing nationally representative data from the 2018 wave of the China Health and Retirement Longitudinal Study (CHARLS), including 5,111 participants aged ≥ 60 years. The SPSS PROCESS macro (Model 6) and Bootstrap were used to examine the serial mediating effect, with subgroup analyses stratified by sleep duration (≤ 6, 6–7, 7–8, > 8 h).

Sleep duration had a direct effect on depressive symptoms [B= -0.548, 95% CI = (-0.628, -0.468)], which accounted for 63.3% of the total effect. Sleep duration was also indirectly associated depressive symptoms through the following three pathways: (1) through SRH [B = -0.123, 95% CI = (-0.148, -0.098)], which accounted for 14.2% of the total effect; (2) through frailty [B = -0.108, 95% CI = (-0.137, -0.080)], which accounted for 12.5%; (3) through SRH and frailty [B = -0.088, 95% CI = (-0.106, -0.072)], which accounted for 10.2%. The total mediating effect was 36.7%. Subgroup analysis results indicated that the serial mediating effect was only present in the group with sleep duration ≤ 6 h.

Self-rated health and frailty have serial mediating effect between sleep duration and depressive symptoms in older adults. Shorter sleep duration correlates with poorer SRH, elevated frailty risk, and increased depressive symptoms. Healthcare professionals should monitor older adults with insufficient sleep and poor SRH to address potential frailty and depressive symptoms.