Association between discretionary screen time and depressive symptoms in Chinese adolescents: a cross-sectional study

Background Adolescents globally exhibit growing engagement with discretionary screen time, but its association with depressive symptoms remains unclear in developing economies. Objective To examine the relationship between discretionary screen time and depressive symptoms among Chinese adolescents. Methods A cross-sectional study of 4,706 adolescents in Maoming City, Guangdong Province, China. Participants were stratified into four discretionary screen time categories: <1 h ( n = 1,372), 1–2 h ( n = 1,277), 2–4 h ( n = 1,032), and ≥4 h ( n = 1,025). Depressive symptoms were assessed using the validated CESD-9, with a cutoff score of ≥10. The primary analysis was a multilevel logistic regression model with random intercepts for school and class, adjusted for all measured covariates except BMI, anxiety and insomnia; a model additionally adjusted for BMI, anxiety and insomnia served as a sensitivity analysis. Subgroup analyses evaluated potential effect modification. Results The prevalence of depressive symptoms was 29.7% (1,398/4,706). In the primary multilevel model (random intercepts for school and class; adjusted for sociodemographic, socioeconomic and lifestyle factors, without BMI, anxiety and insomnia), compared with the <1 h reference group, the odds ratios were 1.21 (95% CI: 0.98–1.49; p = 0.082) for 1–2 h, 1.88 (95% CI: 1.52–2.33; p < 0.001) for 2–4 h, and 2.54 (95% CI: 2.04–3.16; p < 0.001) for ≥4 h; each screen-time category increment was associated with 39% higher odds of depressive symptoms (OR = 1.39, 95% CI: 1.29–1.49; p < 0.001). When additionally adjusted for BMI, anxiety and insomnia (sensitivity analysis, Model 4), the associations were attenuated but remained statistically significant for the higher categories (≥4 h: OR = 1.69, 95% CI: 1.28–2.22; per-category OR = 1.19, 95% CI: 1.09–1.29). Subgroup analyses revealed no statistically significant evidence of effect modification (all p -interaction >0.05). Conclusion Prolonged discretionary screen time is significantly associated with higher odds of depressive symptoms among Chinese adolescents, indicating a graded association that strengthens with increasing screen time. These findings are relevant to public-health monitoring of discretionary screen use in adolescents.