U-shaped association between sleep duration and depression among postmenopausal women: Evidence from a population-based study.

BACKGROUND

Sleep disturbances and depression are prevalent among postmenopausal women, yet their relationship remains unclear. This study investigated the association between sleep duration and depressive symptoms, including severity.

METHODS

This study utilized data from a large nationwide health survey conducted in the U.S between 2007 and 2016, encompassing 4891 eligible postmenopausal women. Depression was assessed using the PHQ-9, and sleep duration was categorized as <7 h (insufficient), 7-8 h (normal), and > 8 h (long). Weighted logistic and multinomial logistic regressions, generalized additive models (GAM), two-piecewise regression, and restricted cubic spline analyses were performed, along with mediation and sensitivity analyses.

RESULTS

The prevalence of depression was 12.2 %. Compared with 7-8 h, both insufficient and long sleep were associated with higher odds of depression (OR = 2.313, 95 % CI: 1.667-3.211; OR = 1.600, 95 % CI: 1.129-2.268). Insufficient sleep showed a dose-response relationship with depressive severity: mild (OR = 1.531), moderate (OR = 2.144), moderately severe (OR = 3.124), and severe (OR = 4.760) (all P < 0.001). Long sleep was related to mild (OR = 1.418), moderately severe (OR = 2.398), and severe depression (OR = 3.282). A U-shaped association was observed, with an inflection at 7.5 h (P for nonlinearity <0.001). The neutrophil-to-lymphocyte ratio showed no mediating effect (β = 0.000042, P = 0.708).

CONCLUSION

Sleep duration shows a U-shaped association with depression in postmenopausal women. Both insufficient and long sleep are associated with greater odds of depression, indicating that sleep duration may be a potentially modifiable correlate of depression.