The mediating role of obesity in the relationship between sleep duration and depressive symptoms: A population-based cross-sectional study

Objective: This study investigates whether obesity mediates the relationship between sleep duration and depressive symptoms, aiming to provide evidence for obesity's mediating effect and inform public health interventions. Methods: Data from 23,190 adults in the National Health and Nutrition Examination Survey (NHANES) 2007-2018 were analyzed. Generalized linear regression models assessed the associations between sleep duration, obesity indicators [body mass index (BMI), waist circumference (WC), and body roundness index (BRI)], and depressive symptoms. Mediation analysis explored the mediating role of obesity, with subgroup analysis across gender, age, and race. Results: Sleep duration was significantly negatively associated with BMI, WC, and BRI (all P < 0.001), and these obesity indicators were positively associated with depressive symptoms (all P < 0.001). Mediation analysis showed that obesity partially mediated the relationship between sleep duration and depressive symptoms, with slightly stronger effects observed in individuals with diabetes. Conclusion: Obesity, assessed by BMI, WC, and BRI, showed a modest, partial mediating role in the association between sleep duration and depressive symptoms, with exploratory evidence of larger indirect effects among individuals with diabetes.