Associations of exercise frequency, exercise session duration, and sleep duration with depressive symptoms among Chinese adolescents: a complex-survey cross-sectional analysis of CFPS2022.

BACKGROUND: Exercise and sleep are modifiable behaviors related to adolescent mental health, but the relevance of specific exercise-frequency categories, participant session duration, and nonlinear sleep duration remains uncertain. METHODS: We analyzed 2,861 adolescents aged 10-19 years from the 2022 China Family Panel Studies. Survey-weighted regression incorporated individual weights, strata, and primary sampling units. Exercise frequency, any exercise participation, participant session duration, and spline-modeled sleep duration were examined in separate models with continuous eight-item Center for Epidemiologic Studies Depression Scale (CES-D8) scores as the primary outcome. RESULTS: CES-D8 scores differed across exercise-frequency categories (p = 0.002), but the pattern was not monotonic. The largest adjusted difference was observed for once-daily exercise vs. never exercising (B = -1.08; 95% CI, -1.62 to -0.53). Any exercise participation was associated with a modestly lower score (B = -0.57; 95% CI, -1.01 to -0.12), whereas session duration among 2,167 exercise participants was not associated with CES-D8 scores (B per 30 min = 0.004; 95% CI, -0.16-0.17). Sleep duration was nonlinearly associated with CES-D8 scores (overall p < 0.001; nonlinearity p = 0.004); relative to 8 h, scores were higher at 6 h (B = 1.03; 95% CI, 0.55-1.51) and 7 h (B = 0.53; 95% CI, 0.30-0.76). Sensitivity analyses were broadly consistent, and multiple-imputation estimates for exercise participation, exercise-frequency contrasts, and sleep-duration contrasts were similar to the complete-case estimates. CONCLUSION: Exercise frequency and sleep duration were modestly associated with depressive-symptom scores, whereas participant session duration showed no clear association. The cross-sectional findings do not establish causality or support a specific exercise prescription.