Objective To explore the relationship between sleep duration and depressive disorder， and further analyze the moderating effects of inflammatory markers， sociodemographic characteristics， and lifestyle factors. Methods Based on the publicly available cross-sectional database of the National Health and Nutrition Examination Survey（ NHANES）， after excluding pregnant women， participants with incomplete demographic data， and those lacking questionnaire assessments of depressive disorder， sleep duration， and physical activity or inflammatory marker tests， a total of 22 201 participants were ultimately included in the analysis. Multivariate Logistic regression and restricted cubic spline were used to analyze the association between sleep duration and depressive disorder， This study delved into the moderating effects of multidimensional factors such as demographic characteristics， lifestyle factors， and inflammatory indicators on the relationship between sleep duration and depressive symptoms and to examine multiplicative interactions across subgroups. Results Of the 22 201 study participants， 1 909 exhibited depressive symptoms（ PHQ-9 score ≥ 10）， resulting in a positive detection rate of 8.6%. Multivariate Logistic regression and restricted cubic spline analysis revealed a U-shaped relationship between sleep duration and depression scores. Both insufficient sleep［ OR=1.76， 95%CI （1.52，2.03）］and excessive sleep［ OR=1.63， 95%CI（ 1.41，1.88）］were associated with an increased risk of depressive disorder， and these differences were statistically significant（ P ＜ 0.05）. Multiplicative interaction analysis revealed a statistically significant interaction between age and sleep duration in relation to depressive disorder（ F=3.389， Pinteraction=0.041）. In addition， smoking， body mass index， physical activity， poverty income ratio， and platelet-to-lymphocyte ratio exerted moderating effects on the association between sleep duration and depressive disorder， with statistically significant differences（ Pinteraction ＜ 0.05）. Conclusions Both insufficient and excessive sleep increase the risk of depressive disorder， particularly among older adults， individuals with high levels of inflammation， those who quit smoking， those with low levels of physical activity and high-income. Sleep health management should be incorporated into depressive disorder prevention and treatment strategies， as ensuring adequate sleep duration helps reduce the risk of depressive disorder.