The Impact of Screen Time and Social Media Use on Adolescent Wellbeing: An Instrumental Variable Analysis

Amid worsening mental health of adolescents, the proliferation of digital technologies over the last two decades has attracted particular attention as one potential contributing factor. However, there is a widely cited lack of causal evidence and most prior studies rely on correlational designs vulnerable to reverse causation, unmeasured confounding, and measurement error, while being limited in geographic scope. We estimate the effects of screen time and social media use on adolescent wellbeing using data from 615,133 fifteen-year-olds across 54 countries, applying instrumental variable methods that exploit cross-national and temporal variation in digital environments during the rapid technological diffusion of the mid-2010s. We use year-specific country-level Information and Communication Technology (ICT) usage index and social media penetration rate as instruments generating exogenous variation in adolescents' digital engagement. Instrumental Variables analyses indicate that higher screen time and more social media use caused lower wellbeing in the mid 2010s. The findings were robust to assumption testing and robustness checks. This study contributes multinational causally informed evidence to an empirically contested but policy-relevant debate on the impacts of digital technology on adolescent wellbeing.