Abnormal night sleep duration and poor sleep quality are independently and combinedly associated with elevated depressive symptoms in Chinese rural adults: Henan Rural Cohort.

Objective: To assess the independent and combined effects of night sleep duration and sleep quality on depressive symptoms.

Methods: A total of 28,202 participants (11,236 males and 16,966 females) aged 18-79 years from the Henan Rural Cohort were included in this study. Night sleep duration and sleep quality were defined by the Pittsburgh Sleep Quality Index (PSQI). Logistic regression and restricted cubic splines were applied to evaluate the association of night sleep duration and sleep quality with depressive symptoms.

Results: A U-shaped dose-response relationship between night sleep duration and depressive symptoms along with a J-shaped relationship between sleep quality and depressive symptoms were observed. Compared with reference group (7-<8 h), shorter sleep duration (<6 h) and longer sleep duration (≥10 h) were associated with increased risk of depressive symptoms in males (short sleep: Odds Ratio (OR) = 1.84, 95% confidence interval (CI), 1.34-2.52; long sleep: OR = 1.56, 95% CI, 1.01-2.42) and females (short sleep: OR = 2.19, 95% CI, 1.77-2.70; long sleep: OR = 1.51, 95% CI, 1.10-2.10). Compared with good sleepers, poor sleepers had 4.23-fold (95% CI:3.54-5.06) and 3.87-fold (95% CI: 3.41-4.40) increased odds of depressive symptoms in males and females. Furthermore, participants with longer night sleep duration (≥10 h) and poorer sleep quality had the strongest effect on depressive symptoms (males: OR = 6.64, 95% CI, 3.21-13.74; females: OR = 7.76, 95% CI, 5.00-12.02).

Conclusions: Extreme night sleep duration and poor sleep quality were independently and combinedly related to elevated depressive symptoms, suggesting that keeping optimal night sleep duration and good sleep quality maybe benefit for maintaining mental health.

Trial Registration: Chinese Clinical Trial Register. Registration number: ChiCTR-OOC-15006699.