DALLAS, Aug. 6, 2025 — A new study published today in the Journal of the American Heart Association reveals a concerning link between excessive screen time and increased risks of cardiometabolic diseases in children and young adults. The research, conducted with over 1,000 participants in Denmark, highlights the potential health risks associated with prolonged use of electronic devices and television.
The study found that increased screen time is significantly associated with higher risks of conditions such as high blood pressure, high cholesterol, and insulin resistance. This association was particularly pronounced among youth who also experienced reduced sleep duration, suggesting that screen time may negatively impact health by reducing sleep.
Research Findings and Implications
According to the study, each additional hour of screen time was linked to an increase in cardiometabolic risk scores among children and adolescents. Dr. David Horner, the study’s lead author from the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) at the University of Copenhagen, emphasized the need for balanced daily routines to protect long-term heart and metabolic health.
“Limiting discretionary screen time in childhood and adolescence may protect long-term heart and metabolic health,” Dr. Horner stated. “Our study provides evidence that this connection starts early and highlights the importance of having balanced daily routines.”
“This means a child with three extra hours of screen time a day would have roughly a quarter to half a standard-deviation higher risk than their peers.” — Dr. David Horner
The analysis also revealed that shorter sleep duration and later sleep timing intensified the relationship between screen time and cardiometabolic risk. In fact, about 12% of the association between screen time and cardiometabolic risk was mediated through shorter sleep duration.
Expert Opinions and Recommendations
Amanda Marma Perak, M.D., chair of the American Heart Association’s Young Hearts Cardiovascular Disease Prevention Committee, who was not involved in the study, suggested that focusing on improving sleep habits could be a practical starting point for reducing screen time.
“If cutting back on screen time feels difficult, start by moving screentime earlier and focusing on getting into bed earlier and for longer,” said Perak.
Dr. Perak also recommended that adults model healthy screen habits for children, emphasizing the importance of setting boundaries and finding non-screen-related activities to engage in.
Study Design and Methodology
The study analyzed data from two groups of children and adolescents in Denmark, part of the COPSAC cohorts. Researchers developed a composite score based on various metabolic syndrome components, including waist size, blood pressure, and cholesterol levels. The findings were adjusted for age and sex to determine the overall risk relative to the study group average.
Screen time was reported through questionnaires, detailing hours spent watching TV, movies, gaming, or using digital devices for leisure. The study found that average screen time increased significantly with age, with 18-year-olds averaging 6.1 hours per day.
Looking Ahead: Potential Interventions
As an observational study, the findings reflect associations rather than causation. However, Dr. Horner suggested that future research could explore interventions such as limiting screen use before bedtime to reduce cardiometabolic risks. This approach could address the disruption of circadian rhythms caused by screen exposure.
Additionally, the study identified a unique metabolic signature associated with screen time, suggesting potential early markers for lifestyle-related health risks. This opens the door for using metabolomic data in lifestyle counseling and preventive health strategies.
As the digital age continues to evolve, understanding the implications of screen time on youth health remains crucial. This study underscores the importance of balanced screen habits and the potential long-term benefits of addressing these behaviors early in life.
