U.S. adolescents spend more than one hour per day on smartphones during school hours, with social media accounting for the largest share of use, according to research published Jan. 5, 2026, in JAMA. The findings have relevance for educators, parents and policymakers.

The study reflects the behavior of 640 adolescents ages 13-18 who were enrolled in the Adolescent Brain Cognitive Development Study. They and their parents had consented to have software placed on their Android cellphones that allowed use to be passively monitored. Usage was measured between September 2022 and May 2024.

Key findings:

• Adolescents spent an average of 1.16 hours per day on smartphones during school hours.
• Social media apps Instagram, TikTok and Snapchat accounted for most use, followed by YouTube and games.
  
• Older adolescents (16–18) and those from lower-income households showed higher smartphone use, compared to peers of the same age.
• “These apps are designed to be addictive. They deprive students of the opportunity to be fully engaged in class and to hone their social skills with classmates and teachers,” said Dr. Dimitri Christakis, the paper’s senior author. He is a professor of pediatrics at the University of Washington School of Medicine and practices at Seattle Children’s Hospital.

Based on a national sample of students, the results build on findings published last year in JAMA Pediatrics. That study had fewer participants but also included iPhone users.  

At least 32 states and the District of Columbia require school districts to ban or restrict students’ use of cellphones in schools. The effect of those policies “remains to be seen,” Christakis said.  

“To date they’ve been very poorly enforced, if at all. I think the U.S. has to recognize the generational implications of depriving children of opportunities to learn in school,” he added. 

The paper’s lead author is Dr. Jason Nagata, an associate professor of pediatrics at the University of California San Francisco.  

“This moves the conversation beyond anecdotes and self-reports to real-world behavior. Teens are not always accurate reporters of their own screen time. Objective smartphone data gives us a clearer picture of actual use,” Nagata said. 

The research was supported by the National Institutes of Health (K08HL159350, R01MH135492, R01DA064134).  

IMAGE CREDIT: NASA.