Joint effects of sleep duration and depressive symptoms on the risk of cardiovascular disease and mediating role of depressive symptoms in middle-aged and older Chinese adults: A nationwide prospective cohort study.

BACKGROUND

Cardiovascular diseases (CVD) are the leading cause of mortality in China. Depression and sleep disturbances are recognized as risk factors for CVD, but their interplay and combined effects remain unclear. This study examines how sleep duration and depressive symptoms interact to influence CVD risk.

METHODS

We analyzed data from five waves of the China Health and Retirement Longitudinal Study (CHARLS) between 2011 and 2020. The final sample included 12,050 individuals aged 45 and above. Sleep duration was categorized as 6 h or less, 6-8 h and > 8 h. Depressive symptoms were assessed using the CESD-10 score and categorized as no depressive symptoms, mild/moderate depressive symptoms, and severe depressive symptoms. Cox proportional hazards models assessed the association between sleep, depressive symptoms, and CVD. Mediation analysis explored the role of depressive symptoms in this relationship.

RESULTS

Short sleep duration was associated with a higher CVD risk (HR 1.19; 95 % CI: 1.03-1.38). Restricted cubic spline (RCS) analysis showed a U-shaped association between sleep duration and CVD risk, with the lowest risk observed at 7.61 h of sleep. Severe depressive symptoms further increased CVD risk when combined with short sleep duration (HR 2.08; 95 % CI: 1.46-2.95) or long sleep duration (HR 2.08; 95 % CI: 1.05-5.35). Mediation analysis revealed that depressive symptoms explained 43.8 % of the total effect of short sleep on CVD.

CONCLUSIONS

Both short sleep and depressive symptoms independently raise the risk of CVD, with depressive symptoms partially mediating the effect of sleep on cardiovascular health. Interventions targeting both sleep and mental health could reduce CVD risk in high-risk populations.