School Phone Bans and Adolescent Mental Health in Iceland

Importance: Concerns about adolescent smartphone use and mental health have prompted many schools to implement mobile phone bans, but evidence of their effects remains mixed. Objective: To examine whether schoolwide mobile phone bans were associated with changes in mental health and associated social and behavioral outcomes among adolescents in Iceland. Design, Setting, and Participants: This repeated cross-sectional study used difference-in-differences analyses of data from 70 schools across 3 waves of the nationwide Youth in Iceland school survey. The surveys were administered to adolescents aged 13 to 15 years in February 2016, February 2018, and November 2023. Analyses were conducted from February 1, 2025, to January 30, 2026. Exposure: Schoolwide mobile phone bans prohibiting student phone use during school hours. Between 2018 and 2023, 22 of 70 schools implemented a phone ban. Main Outcomes and Measures: Primary outcomes were depressive symptoms, anxiety, hostility, and mental well-being. Secondary outcomes were perceived peer support, screen use (social media use, gaming alone, gaming with friends, and video watching), and bullying (in person and cyberbullying). Results: Among 23 938 adolescent observations across the 3 study years, 11 964 (50.0%) were boys; the mean (SD) age was 13.98 (0.82) years. In the postpolicy period from 2018 to 2023, schoolwide mobile phone bans were not associated with meaningful changes in depressive symptoms (β, 0.65 [95% CI, 0.01-1.30]), anxiety (β, 0.21 [95% CI, -0.08 to 0.50]), hostility (β, 0.23 [95% CI, -0.12 to 0.59]), and mental well-being (β, -0.52 [95% CI, -1.08 to 0.03]). Results were similar in gender-stratified analyses and for the secondary outcomes. Sensitivity analyses examining timing of implementation and more stringent phone restriction criteria were consistent with the main findings. Conclusions and Relevance: In this repeated cross-sectional study of adolescents in Iceland, schoolwide mobile phone bans were not associated with meaningful changes in adolescent mental health or related social and behavioral outcomes. These findings suggest that school phone bans implemented in isolation may be insufficient to improve adolescent mental health at the population level.