A study published this month in the journal Pediatrics found that kids who have a smartphone by the age of 12 have a higher risk of poor sleep, depression, and obesity compared to their peers who don’t have the device. In fact, the earlier in life a child gets a smartphone, the more likely they are to develop these health issues.

The research, conducted by doctors at Children’s Hospital Philadelphia, the University of California at Berkeley, and Columbia University, gathered data from over 10,000 adolescents across the U.S. for two years. Their findings were eye-opening: Among the participants, over 63 percent owned a smartphone, and most of those kids had received the phone by the time they were 11. A year after the study was complete, the kids without smartphones had generally better mental health than those with them. Smartphones have legitimate uses, of course, and can play a key role in education and making social connections. But as child psychiatrist Dr. Ran Barzilay, the study’s lead author, notes, the decision to give a child younger then 12 a smartphone is a major one that should be made with care and deliberation. “Most probably, all teens will eventually have a smartphone,” he said. “Once this happens, it is advisable to monitor what our children do on their phones.” “Eventually” might come sooner than Dr. Barzilay knows—according to the Pew Research Center, 95 percent of teens between the ages of 13 and 17 owned a smartphone in 2024.