NEW YORK – There have been increasingly loud public warnings that social media is harming teenagers’ mental health – most recently from the United States surgeon general – adding to many parents’ fears about what all the time spent on phones is doing to their children’s brains.

Although many scientists share the concern, there is little research to prove that social media is harmful – or to indicate which sites, apps or features are problematic. There is not even a shared definition of what social media is. It leaves parents, policymakers and other adults in teenagers’ lives without clear guidance on what to be worried about.

“We have some evidence to guide us, but this is a scenario in which we just need to know more,” said psychologist Jacqueline Nesi, from Brown University in Providence, Rhode Island, who studies the topic.

What counts as social media when it comes to teenagers’ health?

The surgeon general, Dr Vivek Murthy, warned in May that social media carried a profound risk of harm, but did not name any apps or websites. His report acknowledged that “there isn’t a single, widely accepted scholarly definition of social media”.

Most studies look at platforms with user-generated content, where people can interact. But that raises many questions. Does it matter if teenagers see posts from people they know or do not know? Does it make a difference if they post or just view? Do multiplayer games count? Dating apps? Group texts?

YouTube illustrates the challenge. It is the most popular site among teenagers by far: 95 per cent use it, and almost 20 per cent say they do so “almost constantly”, Pew Research Center found. It has all the features of social media, yet it has not been included in most studies.

Some researchers speculated that YouTube may not have as many detrimental effects because teenagers often consume it passively, like TV, and do not post or comment as often as they do on other apps. Or, researchers said, it may carry the same risks – it offers endless scrolling and algorithmic recommendations, similar to TikTok. There is no clear data either way.

What do we not know?

Reviews of the existing studies on social media use and adolescents’ mental health have found the bulk of them to be “weak”, “inconsistent”, “inconclusive” and “a bag of mixed findings”, and to be “weighed down by a lack of quality” and “conflicting evidence”.

Research has not yet shown which sites, apps or features of social media have which effects on mental health.

“We don’t have enough evidence to tell parents to get rid of a particular app, or cut it off after a particular number of hours,” said Dr Sophia Choukas-Bradley, a psychologist and director of the Teen and Young Adult Lab at the University of Pittsburgh.

It is also hard to prove that social media causes poor mental health, versus being correlated with it. Most studies measure time spent on social media and mental health symptoms, and many, though not all, have found a correlation.

But other researchers say measuring time spent is not enough. In these studies, it is unclear if time on social media is the problem, or if it is time away from other things such as exercising or sleeping. And the studies obscure, for instance, if someone is spending hours on screens to escape mental duress or to seek support from friends.

A few studies have tried novel approaches around these problems. One, early in Facebook’s rollout in the mid-2000s, compared college campuses that had received access to it with those that had not, and found that its arrival had a negative effect on students’ mental health.

A carefully designed study – Project Awesome, at the University of Amsterdam and Erasmus University, in Rotterdam, the Netherlands – looks at the average effects of social media on 1,000 teenagers it surveys and how they differ by individual, and follows adolescents over time. It has found that time spent on social media is less of a factor than teenagers’ moods while using it.

Other studies have used brain scans to show that when adolescents looked at likes or frequently checked feeds, it activated brain sensitivity to social rewards and punishments.

Why isn’t there more solid research?

Academic research takes a long time – often years – to get funding, develop studies, hire staff, recruit participants, analyse data and submit for publication. Recruiting minors is even harder. By the time a study is out, teenagers have often moved on to a different platform. Much of the research about specific platforms, for example, is on Facebook, which most teens no longer use. Tech companies have also not shared enough data to help researchers understand their products’ impacts, said the surgeon general’s report.

How could future studies be more conclusive?

Experts said they would like to see research that examines specific types of social media content, and things such as how social media use in adolescence affects people in adulthood, what it does to neural pathways and how to protect youth against negative effects.

Psychologists Jonathan Haidt and Jean Twenge, who have both expressed great concern about social media’s effect on teenagers, have proposed an experiment in which entire middle schools are randomly assigned to avoid social media or not.

What should parents do in the meantime?

Experts agreed that waiting for research was not an option. They also mostly agreed that some level of social media use was beneficial.

“There are harmful negative developmental implications to not using social media at all, given this is where the social interaction happens,” said Dr Choukas-Bradley.

Researchers said social media rules should depend on individual teenagers’ maturity and their challenges, and added that addressing the risks should also be the responsibility of tech companies and policymakers, not just parents. They agreed on a few steps parents could take now:

• Set limits, especially around bedtime.
• Do not give a young teenager a smartphone right away. Start with a smartwatch or a phone without Internet.
• Talk to your teenagers. Have them show you what they are seeing, ask them how it makes them feel, and discuss privacy and safety.
• Make a family screen-time plan that takes into account which activities increase stress versus providing long-term satisfaction.
• Model responsible Internet use yourself.

It is not about monitoring certain apps, said Dr Caleb Carr, a professor of communication at Illinois State. He added: “Instead, parents should engage with their kids. Just like parents did pre-social media, talk about being good humans and citizens, talk about respect for others and themselves, and talk about how their day was.” NYTIMES