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:
“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).
Related: Among U.S. adults, 71.3% supported the banning of smartphones in schools, according to a companion research letter published in JAMA Pediatrics . For that paper, the researchers analyzed a 2023 survey of 35,000 adults in 35 countries.
JAMA
Data/statistical analysis
People
Smartphone Use During School Hours by US Youth in the Adolescent Brain Cognitive Development Study
5-Jan-2026
Dr Nagata reported receiving grants from the National Institutes of Health (NIH) during the conduct of the study. Dr Hale reported receiving personal fees from the National Sleep Foundation for chairing the Screens and Sleep Consensus Panel and from the Children and Screens Institute for co-editing a handbook; receiving grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and Della Pietra Family Foundation; and serving as an expert witness for social media litigation outside the submitted work. Dr Baker reported receiving grants from the NIH during the conduct of the study. Dr Christakis reported serving as an expert consultant in social media litigation for Motley Rice outside the submitted work. No other disclosures were reported.