U.S. Surgeon General Vivek Murthy made waves this week when he said on CNN that 13-year-olds are too young to join social media sites, citing concerns about mental health. Many sites, like Meta’s Facebook and Instagram, limit membership to users 13 and older, partly as a consequence of the Children’s Online Privacy Protection Act, a federal law that imposes greater restrictions on collecting personal data from younger kids. 

Keeping teens off social media may be easier said than done, especially in an era when Instagram and TikTok and Snapchat have become ubiquitous, and when kids without accounts on those platforms may struggle to connect with friends. Seattle Public Schools, which made headlines earlier this month by suing the big social media companies over alleged mental health harms to its students, emphasized that it wants the tech giants to do more to help kids.

To Murthy’s point, studies do suggest that there can be negative consequences for children and adolescents who use social media.

Social media is associated with body and self-esteem issues in kids and teens. A Université de Montréal study published in Psychology & Health in November found that teens who use social media more frequently than their peers are more likely to have self-esteem issues and symptoms of eating disorders. In addition, a recent survey by U.K.-based teen mental health nonprofit Stem4 found that nearly half of participants ages 12 to 21 exhibited unhealthy symptoms after they were “regularly bullied or trolled online about their physical appearance.” Users who compare themselves to other users (both people they know and celebrities) are more likely to exhibit low self-esteem and depression, and teen girls may be particularly affected, some studies indicate.
More time on social media might correlate with more depressive symptoms. Some studies find that young people who spend more hours on social media may have a heightened risk of developing mental health disorders. A 2020 report in the Dana Foundation’s Cerebrum magazine suggests the situation may vary from person to person, with teens who already have healthier social lives faring better on social media than those who are already struggling socially. 
Regular checking of social media may influence brain development. A recent study published in JAMA Pediatrics shows that frequent checking of social apps “may be longitudinally associated with changes in neural sensitivity to anticipation of social rewards and punishments, which could have implications for psychological adjustment.” Though as with most factors affecting the complex development of the brain, knowing exactly what the effects of social media and other apps are—and even whether those effects are positive or negative—can prove difficult.
Adult brains may be more resistant to social media effects. Adults tend to have a more established sense of self, are less subject to pressure from peer feedback, and have a more developed prefrontal cortex, a part of the brain that helps regulate mental response to social stimuli, according to a report from the American Psychological Association last year. Behaviors that can lead to problems, like comparing oneself to others on social media, seem to be more prevalent among younger users.

Social media continues to evolve rapidly, as more and newer apps become popular among teens and existing products introduce new features over time. As Murthy points out, social media companies do extensive R&D to maximize the time people spend on their platforms, and they typically don’t release their internal research to the public. That leaves outside scientists playing catch-up to determine the effects of social media on users—and what users, app makers, parents, and society as a whole can do to make social media healthier.