Adolescents who spend over three hours a day engaging in sedentary behaviors, such as playing video games, reading for leisure or being frequently distracted by screens, have an increased likelihood of experiencing psychological distress later on, according to research published in the Journal of Adolescent Health. In contrast, moderate screen exposure—between 60 and 119 minutes daily—for educational purposes like doing homework or attending classes—is identified as a “protective” factor linked to lower levels of psychological distress.
Sedentary behavior among adolescents is a growing concern worldwide, with significant consequences for both physical and mental health in this age group. Multiple studies have shown that lack of physical activity combined with excessive use of electronic devices contributes to issues like obesity and cardiovascular disease. Additionally, accumulating research indicates that the effects of a sedentary lifestyle extend beyond the physical body, influencing mental health by increasing anxiety and depression.
The study was conducted at King’s College London’s Institute of Psychiatry, Psychology & Neuroscience in the UK. It analyzed data from 3,675 adolescents involved in the Millennium Cohort Study—a project tracking children born between 2000 and 2002 with a large database. The research examined sedentary behavior twice: at age 14 and then again at age 17.
At age 14, participants recorded their activities every ten minutes in diaries, which were categorized into broader contexts such as general physical activity, sleep time, recreational screen use, non-screen leisure activities, and educational sedentary behavior. At age 17, the same individuals reported their psychological distress using a six-question Kessler Scale questionnaire about how often they felt nervous, hopeless, restless, depressed, anxious or socially isolated.
Interestingly—and unexpectedly—researchers found that adolescents who spent more than three hours daily reading for leisure (especially boys) also experienced higher levels of psychological distress. Although previous studies link reading to better mental health and other positive behaviors, this new research suggests excessive reading may be harmful in certain cases. A possible explanation is that prolonged reading might displace time needed for face-to-face or outdoor social interactions, which are protective against isolation.
Moreover, screen devices used for reading could potentially disrupt sleep due to blue light exposure. However, according to Professor Brendon Stubbs who supervised the study, “Our main finding…is that more leisure screen time was associated with worse psychological distress while more time in educational activities was associated with less distress.”
Based on these findings, researchers suggest interventions aimed at minimizing negative effects of excessive sedentary behavior:
- Limits on Screen Time: Implement guidelines limiting recreational screen use to under three hours daily.
- Focusing on Context: Promote structured educational and active screen activities over passive leisure time.
- Balancing Activities: Encourage alternative leisure activities that involve social interactions, as isolated screen time can lead to psychological distress.
- Gender-Specific Approaches: Tailor interventions based on gender differences (e.g., girls spending more time online browsing while boys prefer video games).
- Educational Support: Ensure adequate academic engagement since moderate amounts of homework and class time are associated with lower psychological distress.
- Managing Screen Time: Focus on optimizing screen use rather than eliminating it altogether.
Werneck concludes that interventions must address the complexity of sedentary behavior, taking into account specific activities and contexts. He advocates for strategies to reduce long periods in particularly distress-linked sedentary activities rather than reducing all such behaviors universally.
