USA - A study published today in the journal JAMA Psychiatry suggests that teenagers who spend more than three hours a day on social media are more likely to develop mental health problems including depression, anxiety, aggression, and antisocial behavior. The study: Nearly 6,600 12- to 15-year-old Americans self-reported how much time they spent per day on social media, as well as whether they had any mental health problems. The researchers found that three hours of social media correlated with higher rates of mental health issues, even after adjusting for a history of such problems. How teens absorb social media: The effects of social-media consumption on teens manifest in two main ways, according to the study’s authors: internally (depression and anxiety, for example) and externally (aggressive behavior or antisocial behavior). The latter were essentially nonexistent among teens who reported that they didn’t use social media.