Smartphone addiction, physical activity engagement, and sleep quality in Chinese adolescents: a parallel and serial mediation model

Abstract

Excessive smartphone use has become a major public health concern among adolescents, particularly in China where smartphone use is widespread. Although smartphone addiction is consistently associated with poor sleep quality, the mechanisms underlying this association remain insufficiently understood. This study examined whether physical activity engagement and depressive symptoms operate as parallel and serial mediators linking smartphone addiction to sleep quality in Chinese adolescents. A cross-sectional survey was conducted among 612 adolescents (Mage = 14.2 years, SD = 1.6; 51.3% female) from four secondary schools in Hubei Province, China. Participants completed the Smartphone Addiction Scale–Short Version, the Physical Activity Questionnaire for Adolescents, the Pittsburgh Sleep Quality Index, and the Depression subscale of the Depression Anxiety Stress Scales-21. Path analysis of observed composite scores with robust maximum likelihood estimation and bias-corrected bootstrapping (5,000 resamples) was used to test the proposed parallel and serial mediation model. Smartphone addiction was positively associated with poor sleep quality (β = .38, p <.001). Both physical activity (indirect effect = .04, 95% CI [.01,.07]) and depressive symptoms (indirect effect = .14, 95% CI [.09,.19]) significantly mediated this association in parallel. In addition, the serial pathway from smartphone addiction to low physical activity, elevated depressive symptoms, and poor sleep quality was significant (indirect effect = .02, 95% CI [.01,.04]). The mediators collectively accounted for 52.6% of the total effect. These findings suggest that problematic smartphone use is associated with poorer adolescent sleep through behavioral and psychological pathways involving reduced physical activity and elevated depressive symptoms. School-based interventions that promote physical activity while reducing problematic smartphone use may help protect adolescent sleep and mental health. Longitudinal and experimental designs are needed to establish causal direction and inform intervention development.