Brief report: Longitudinal associations between physical activity, sleep disturbance and depressive symptoms in adolescent girls

Introduction: Physical activity (PA) and sleep disturbances (SD) are related with depressive symptoms in adults. However, evidence that PA and SD are prospectively associated with depression is mixed. The aim of this study was to examine longitudinal and bidirectional associations between PA, SD and depressive symptoms in adolescent girls. Methods: A 2-year longitudinal study was conducted consisting of three waves, each separated by 1 year. The participants were 173 Estonian adolescent girls aged 14.3 +/- 0.4 years (M +/- SD) who individually completed self-report measures of PA, SD and depressive symptoms. Results: Latent growth modelling indicated that the increase in depressive symptoms was associated with an increase in SD and a decrease in PA. Baseline levels of depressive symptoms were predictive of changes in PA and SD, but not the other way around. Moreover, initial SD predicted decrease in PA. Conclusions: High levels of depressive symptoms at baseline were associated with lower PA and higher SD after two years but not vice versa in adolescent girls.