Question: Is social media use associated with well-being across adolescent development, and do these associations differ by sex and developmental stage?
Findings: In this cohort study of 100 991 Australian adolescents (grades 4-12) followed up for 3 years, a U-shaped association emerged where moderate social media use was associated with the best well-being outcomes, while both no use and highest use were associated with poorer well-being. For girls, moderate use became most favorable from middle adolescence onward, while for boys, no use became increasingly problematic from midadolescence, exceeding risks of high use by late adolescence.
Meaning: Social media’s association with adolescent well-being is complex and nonlinear, suggesting that both abstinence and excessive use can be problematic depending on developmental stage and sex.