The association between physical activity and depressive symptoms in U.S. adults is modulated by sleep duration: gender disparities.

Background: The joint effects of physical activity and sleep duration on depression remain unclear. The aim of this study is to explore the independent and joint associations between physical activity (PA) and sleep duration with depressive symptoms.

Methods: We included and analyzed 18,052 participants (age ≥ 20 years) from the cross-sectional National Health and Nutrition Examination Survey (NHANES) conducted between 2007 and 2014.

Results: After adjustment, both males and females showed a significant correlation between PA, sleep duration, and depressive symptoms. In the joint association analysis, we found: 1. The interaction between PA and sleep duration was statistically significant in males but not significant in females (P = 0.380). 2. Compared to individuals with the lowest PA level and not meeting the National Sleep Foundation's (NSF) guidelines, those with the highest PA level and recommended sleep duration had a 79% decrease in depression risk in males (odds ratio [OR] 0.21, 95% confidence interval [CI] 0.14-0.32) and a 74% decrease in females (OR 0.26, 95% CI 0.20-0.35). 3. In male participants adhering to NSF guidelines, each increase in PA quartile is associated with a 19% reduction in the risk of depression (OR 0.81, 95% CI 0.71-0.92). Conversely, among male participants not adhering to NSF guidelines, there is a 23% decrease in depression risk (OR 0.77, 95% CI 0.69-0.86). For female participants, the respective reductions in depression risk are 20% (OR 0.80, 95% CI 0.73-0.89) and 14% (OR 0.86, 95% CI 0.80-0.93).

Conclusion: For males, adherence to recommended sleep duration weakens the relationship between physical activity and depression, while the opposite is observed for females.