Physical activity and health-related quality of life among Chinese adolescents: a cross-sectional statistical path model involving sleep disturbance and depressive symptoms.

OBJECTIVE: Physical activity (PA) is positively associated with health-related quality of life (HRQoL) in adolescents, while sleep disturbance and depressive symptoms are also closely related to both PA and HRQoL. However, relatively few studies have examined these factors simultaneously, particularly among Chinese adolescents. This study examined the association between PA and HRQoL and assessed the separate and serial indirect associations involving sleep disturbance and depressive symptoms. METHODS: A cross-sectional survey was conducted among 2,202 secondary-school students from 12 schools in China. Participants completed validated self-report measures of PA, sleep disturbance, depressive symptoms, and HRQoL. Pearson correlations were used to examine bivariate associations, and a serial multiple-mediator model (PROCESS Model 6) was applied to estimate direct and indirect associations. Statistical uncertainty was evaluated using 5,000 bootstrap resamples and bias-corrected 95% confidence intervals (CIs). RESULTS: Higher PA was associated with lower sleep disturbance and depressive symptoms and with better HRQoL. Sleep disturbance was positively associated with depressive symptoms, whereas both sleep disturbance and depressive symptoms were inversely associated with HRQoL. The standardized total association between PA and HRQoL was 0.324 [95% CI (0.288, 0.358)], of which 0.095 was statistically accounted for by the combined indirect associations. Significant specific indirect associations were observed through sleep disturbance alone [β = 0.032, 95% CI (0.019, 0.046)], depressive symptoms alone [β = 0.046, 95% CI (0.034, 0.058)], and the sequential pathway involving sleep disturbance followed by depressive symptoms [β = 0.017, 95% CI (0.013, 0.022)]. The direct PA-HRQoL association remained significant after both statistical mediators were included [β = 0.229, 95% CI (0.191, 0.265)]. CONCLUSIONS: PA, sleep disturbance, depressive symptoms, and HRQoL were closely interconnected among Chinese adolescents. Sleep- and mood-related factors statistically accounted for part of the positive association between PA and HRQoL, with depressive symptoms showing the largest specific indirect association. These findings support considering PA, sleep health, and emotional well-being within an integrated adolescent health framework. Because all variables were measured concurrently, the observed indirect associations should not be interpreted as evidence of temporal or causal mediation.