Table 2_Association between discretionary screen time and depressive symptoms in Chinese adolescents: a cross-sectional study.docx

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).</p>Conclusion<p>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.</p>