Jason Nagata, MD, MSc, highlights frequent teen smartphone use during school hours

Jason Nagata, MD, MSc, associate professor at the University of California, San Francisco, discusses why it is increasingly important to evaluate adolescent smartphone use using objective data, particularly as school phone policies rapidly evolve across the United States.

By 2026, most public school districts are expected to have formal phone policies in place. However, much of the existing evidence guiding these policies has relied on adolescents’ self-reported phone use, which can be inaccurate. Nagata explains that his study adds value by providing objective data on how smartphones are actually used during the school day, offering a clearer picture of real-world behavior rather than perceptions or anecdotes.

According to the study’s findings, adolescents spend, on average, more than 1 hour per day on their smartphones during school hours. The most commonly used apps include social media platforms, YouTube, and video games—forms of content that are generally unrelated to academic tasks.

Nagata emphasizes that this type of screen use likely detracts from attention to classroom learning and educational activities. He notes that highly engaging, short-form, visually stimulating content driven by artificial intelligence algorithms may condition adolescents toward shorter attention spans, making it more difficult to sustain focus on deep, meaningful learning.

Beyond academics, Nagata highlights broader developmental concerns. Smartphone use during recess or lunch can replace face-to-face interactions with peers, limiting opportunities to develop critical social skills. Additionally, time spent on phones often displaces physical activity, which is essential for both physical health and mental well-being. Collectively, these factors suggest that smartphone use during school hours may interfere with multiple domains of adolescent development, including cognitive, social, and emotional growth.

Nagata explains that while many schools have implemented phone restrictions, the study reveals uneven enforcement. Even in districts with established policies, many students are still able to access their phones for extended periods during the school day. This underscores the need for educators, administrators, and parents to recognize gaps between policy intent and real-world implementation when shaping future guidelines.

To support healthy development, Nagata points to recommendations from the American Academy of Pediatrics, including the use of a family media plan. Such plans encourage ongoing family discussions about age-appropriate rules, device access, and setting limits during key times such as school hours, meals, and bedtime.

He also stresses the role of schools in promoting digital literacy and balanced technology use. Ultimately, the study’s key contribution is providing objective evidence that smartphones remain a significant presence in adolescents’ daily lives—even during school—helping shift the policy conversation from self-reports to measurable behavior.

No relevant disclosures.

Reference

Nagata JM, Kim KE, Huang OH, et al. Smartphone use during school hours by US youth in the adolescent brain cognitive development study. JAMA. 2026. doi:10.1001/jama.2025.23235