Having a smartphone may be harmful for children younger than 12, according to a new study.

The study published Monday in the peer-reviewed journal Pediatrics found that owning a smartphone during early adolescence is associated with increased risks of mental health issues and obesity. As far as psychological impacts, it pinpointed higher incidences of depression and insufficient sleep among children who owned smartphones by ages 12 or younger, compared with others kids without the devices.

Researchers at Children's Hospital Philadelphia, the University of California at Berkeley, and Columbia University arrived at those conclusions after analyzing data from more than 10,000 adolescents around the United States who participated in the Adolescent Brain Cognitive Development Study (ABCD) between 2018 and 2020. That study, funded by the National Institutes of Health, describes itself as "the largest long-term study of brain development and child health" in the country.

According to researchers, 63.6% of the ABCD study's participants owned a smartphone, and the medium age they received them was at 11 years old. Using that data, the researchers determined that younger children had greater risks than older participants of poor sleep or obesity linked to smartphone ownership — with worse health outcomes reported for kids the younger they were when they received their first smartphone.

The Pediatrics study also compared children who had obtained a smartphone by age 12 and children who had not, and found that one year later, those without smartphones were experiencing better mental health than those who had them.

"Our findings suggest that we should view smartphones as a significant factor in teen health, approaching the decision to give a child a phone with care and considering potential impacts on their life and health," said Ran Barzilay, the lead author of the study and a child psychiatrist with the Youth Suicide Prevention, Intervention and Research Center at the Children's Hospital of Philadelphia, in a statement. "We're not claiming smartphones are detrimental to all adolescents' health; rather, we advocate for thoughtful consideration of the health implications, balancing both positive and negative consequences."

Barzilay said smartphones "can play a constructive role" in teens' lives by strengthening their social connections and helping them learn, in part by giving them easier access to information that has potential to bolster their personal growth. He added that some families see smartphones as necessary for their children's safety.

Going forward, Barzilay said the researchers behind the study hope to investigate which aspects of smartphone use and ownership are connected with negative health effects for young people. They intend to study younger children, who acquired smartphones before age 10, in an effort to understand who is most vulnerable to the detrimental impacts of smartphone use who and who could most benefit from it. Ultimately, Barzilay said the goal is to identify ways to protect children and adolescents who own smartphones from the consequences outlined in their findings.

In recent years, a growing number of experts have sounded the alarm about increased screen time and the effect it has on kids and teens. In a 2023 advisory on social media use and mental health, former U.S. Surgeon General Dr. Vivek Murthy recommended creating "tech-free zones" and encouraging kids to "foster in-person friendships." Meanwhile, several states have taken steps to ban cellphones in schools.

According to Pew Research Center, 95% of teens between the ages of 13 and 17 owned a smartphone in 2024. More than half of parents with children between the ages of 11 and 12 who were surveyed by the research center at that time said their kids also owned smartphones. The same survey found that nearly 30% of parents with children between 8 and 10 years old said their kids owned smartphones, as did 12% of parents with children between 5 and 7 years old, and 8% of parents with children younger than 5.

"Most probably, all teens will eventually have a smartphone," said Barzilay. "Once this happens, it is advisable to monitor what our children do on their phones, ensuring they're not exposed to inappropriate content and that smartphones don't disrupt sleep."

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