A cross-sectional study of the association between physical activity and depressive symptoms among adolescents in southwest China stratified by parental absence: the mediating role of insomnia and the moderating role of resilience

Objectives This study explored the mechanisms by which physical activity was associated with depressive symptoms in multi-ethnic (Han, Yi and Tibetan) adolescents in southwest China. The mediating role of insomnia in the association of physical activity with depressive symptoms, the moderating role of resilience in this mediation model and the moderating role of parental absence in the moderated mediation model were also examined. Design A cross-sectional survey. Setting In southwest China (Sichuan Province and Tibet Autonomous Region). Participants 3195 adolescents from a school-based survey conducted between April and October 2020. Methods There were 3143 valid samples in this study (47.2% males with mean age=12.88 +/- 1.68 years). Structural equation models were developed to estimate the direct and mediating effect, and the moderating effect. Multigroup comparison was performed to examine the differences and similarities of the moderated mediation model across three parental absence subgroups: (1) both parents present, (2) one parent absent and (3) both parents absent. Results As hypothesised, physical activity was significantly and positively associated with the reduction of depressive symptoms in adolescents. Insomnia partially mediated the effect of physical activity on depressive symptoms. In addition, resilience moderated the direct and indirect effects of physical activity (through insomnia) on depressive symptoms. Finally, the multigroup comparison indicated the moderating effect of parental absence on the moderated mediation model. Conclusions Physical activity was associated with alleviating insomnia symptoms among adolescents, thus correlating with the improvement of their depressive symptoms. Resilience was associated with enhancing the beneficial effects of physical activity, further improving depressive symptoms among adolescents, especially those with both absent parents. It is evident that physical activity interventions should be further incorporated into public health programmes to foster the physical and mental health of left-behind adolescents in southwest China.