Screen Time and Adolescent Internalizing Disorders: A Systematic Review and Dose-Response Meta-Analysis

Abstract

Introduction: Adolescent mental health has been linked to screen time, but whether a causal relationship exists with internalizing disorders (anxiety, depression) remains debated. Previous reviews are limited by cross-sectional designs and failure to examine dose-response relationships. This review quantifies the prospective association between screen time and subsequent internalizing symptoms.

Methods: We searched PubMed, PsycINFO, and Scopus for longitudinal cohort studies (≥12 months follow-up) of adolescents (10–19 years) reporting baseline total recreational screen time (hours/day) and follow-up internalizing symptoms (validated scales). Primary outcome: adjusted odds ratio (aOR) for developing elevated symptoms (top quartile or clinical cutoff). One-stage dose-response meta-analysis using restricted cubic splines modeled continuous screen time. Secondary outcome: effect modification by screen type (social media, gaming, general internet).

Results: Twenty-three cohorts (n=98,471 adolescents) were included. Compared to 1 hour/day, the aOR for internalizing disorders at 4 hours/day was 1.32 (95% CI 1.18–1.48), at 6 hours/day 1.58 (1.38–1.81), and at 8 hours/day 1.89 (1.58–2.26). The dose-response curve was non-linear: steep increase from 1–4 hours (slope 0.11 per hour), then plateauing beyond 6 hours. Social media had the strongest association (aOR at 4 hours/day 1.52), followed by general internet (1.28), then gaming (1.12). Girls showed larger effects (aOR 1.72 vs. 1.34 in boys at 6 hours/day, p-for-interaction=0.02). Heterogeneity was moderate (I²=48%).

Discussion: Screen time shows a monotonic, non-linear association with adolescent internalizing disorders, with no safe threshold exceeding 4 hours/day. Social media appears most harmful, potentially via social comparison and sleep displacement. Reverse causality (depressed adolescents seeking screens) cannot be excluded, but most studies adjusted for baseline symptoms. Limitations include self-reported screen time and lack of active content measures.

Conclusions: Limiting recreational screen time to ≤4 hours/day, particularly social media, may reduce adolescent internalizing disorder risk. Girls may be more vulnerable. Causal inference requires RCTs of screen reduction interventions.