When Surgeon General Dr. Vivek Murthy announced Monday that he was planning to push for a mental health warning label on social media platforms, he was met with cheers from many parents and teachers, who described a long, lonely struggle to wrench children away from a habit that was hurting them.

He got a cooler reaction, however, from some scientists who study the relationship between social media and mental health. In interviews, several researchers said the blanket warning that Murthy has proposed — “social media is associated with significant mental health harms for adolescents” — stretches and oversimplifies the scientific evidence.

For many years, researchers have tried to determine whether the amount of time a child spent on social media contributed to poor mental health, and “the results have been really mixed, with probably the consensus being that no, it’s not related,” said Mitch Prinstein, the chief science officer at the American Psychological Association.

What seems to matter more, he said, is what they are doing online — content about self-harm, for example, has been shown to increase self-harming behavior.

“It’s kind of like saying, ‘Is the number of calories that you eat good for you or bad for you?’ ” Prinstein said. “It depends. Is it candy, or is it vegetables? If your child is spending all day on social media following The New York Times feed and talking about it with their friends, that’s probably fine, you know?”

Like other scientists interviewed, Prinstein applauded Murthy for drawing attention to the mental health crisis. He said he was very optimistic about policy changes that might follow, to keep social media use from interfering with school, sleep and physical activity. After Murthy’s announcement, California Gov. Gavin Newsom called for a statewide ban on smartphone use in California schools.

“What’s happening out there, and what I think the surgeon general has tapped into so well, is that parents are feeling so incredibly helpless,” Prinstein said. “He’s giving some ammunition to everyone in this conversation to say, ‘Look — I don’t care how much my child may be upset with me, if the surgeon general says this might be harmful, I feel justified in taking away the device at 9 p.m.’ ”

In his essay laying out the case for a warning label, published Monday in the Times, Murthy leaned more heavily on anecdotes than on scientific research. He cited one 2019 study, which found that adolescents who spent more than three hours a day on social media faced double the risk of anxiety and depression symptoms.

Murthy has ready responses to his academic critics. He says children growing up now “don’t have the luxury of waiting years until we know the full extent of social media’s impact.” When challenged for evidence of social media’s harmful effects, he argues instead that “we do not have enough evidence to conclude that social media is sufficiently safe.”

“The warning label is important until we can get to the point where social media is actually safe,” he said in an interview.

In interviews, several researchers said the proposed warning was overly broad and could backfire.

Even before Murthy’s announcement, a number of researchers were challenging the widely accepted link between social media and the mental health crisis. That debate intensified after the March publication of “The Anxious Generation,” by Jonathan Haidt, a professor at New York University’s business school, which argued that the spread of social media had led to “an epidemic of mental illness.”

The book was panned in the journal Nature by Candice Odgers, a professor of psychological science in informatics at the University of California, Irvine. “Hundreds of researchers, myself included, have searched for the kind of large effects suggested by Haidt,” she wrote. “Our efforts have produced a mix of no, small and mixed associations.”