Smartphone Era Linked to Teen Depression

New longitudinal and experimental evidence converges on a model where the rapid adoption of smartphones and social media after ~2012 produced a population‑level change in teens' time use (less in‑person socializing and sleep) that plausibly increased rates of depression and anxiety, particularly among heavy users and teenage girls. The signal is not just a small correlation but a cohort‑level inflection visible across surveys, time‑use data and some causal designs. — If true, this reframes youth mental‑health policy toward regulating platform design, limiting adolescent screen exposure, and directing school and clinical resources to cohorts exposed to intense social‑media use.