A new study links excessive screen time in children and teens to higher risks of high blood pressure, cholesterol, and insulin resistance, especially when sleep is limited
Children and teens who spend long hours on screens may be setting themselves up for serious long-term health risks. New research published in the Journal of the American Heart Association reveals that more time spent on phones, TVs, or gaming devices is linked to elevated markers for heart disease, diabetes, and other metabolic conditions, particularly in those who also get less sleep.
“Limiting discretionary screen time in childhood and adolescence may protect long-term heart and metabolic health,” said study lead author David Horner, M.D., PhD., a researcher at the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) at the University of Copenhagen in Denmark. “Our study provides evidence that this connection starts early and highlights the importance of having balanced daily routines.”
Extracting data to understand the link between screentime and cardiometabolic risk factors
The researchers used data from a group of ten-year-olds in 2010 and a group of 18-year-olds in 2000 that were part of the Copenhagen Prospective Studies on Asthma in Childhood cohorts, to understand the relationship between excessive screen time and cardiometabolic risk factors.
The team developed a composite score based on a cluster of metabolic syndrome components, including waist size, blood pressure, high-density lipoprotein or HDL “good” cholesterol, triglycerides, and blood sugar levels, and adjusted for sex and age. The cardiometabolic score reflected a participant’s overall risk relative to the study group average (measured in standard deviations): 0 means average risk, and 1 means one standard deviation above average.
Each extra hour of screentime increased children’s risk
The researchers found that each subsequent hour of screen time increased the cardiometabolic score by around 0.08 standard deviations in the 10-year-olds and 0.13 standard deviations in the 18-year-olds. “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,” Horner said.
“It’s a small change per hour, but when screen time accumulates to three, five or even six hours a day, as we saw in many adolescents, that adds up,” he said. “Multiply that across a whole population of children, and you’re looking at a meaningful shift in early cardiometabolic risk that could carry into adulthood.”
The analysis revealed that both sleep duration and sleep timing play a crucial role in the relationship between excessive screen time and cardiometabolic risk. Shorter sleep duration and going to sleep later intensified this relationship, with children and adolescents who had less sleep showing a significantly higher risk associated with the same amount of screen time.
“In childhood, sleep duration not only moderated this relationship but also partially explained it: about 12% of the association between screen time and cardiometabolic risk was mediated through shorter sleep duration,” Horner said. “These findings suggest that insufficient sleep may not only magnify the impact of screen time but could be a key pathway linking screen habits to early metabolic changes.”
A machine learning analysis also identified a unique metabolic signature in the blood that appeared to be associated with excessive screen time.
The study was able to identify a set of blood-metabolite changes, or a ‘screentime fingerprint’, which validates the potential biological impact of screen time behavior. Using the same data, the study also assessed whether screen time was linked to predicted cardiovascular risk in adulthood, finding a positive trend in childhood and a significant association in adolescence. This suggests that screen-related metabolic changes may provide early signals of long-term heart health risk.
“Recognizing and discussing screen habits during pediatric appointments could become part of broader lifestyle counseling, much like diet or physical activity,” he said. “These results also open the door to using metabolomic signatures as early objective markers of lifestyle risk.”
“If cutting back on screen time feels difficult, start by moving screentime earlier and focusing on getting into bed earlier and for longer,” said Amanda Marma Perak, an assistant professor of pediatrics and preventive medicine at Northwestern University Feinberg School of Medicine in Chicago.
Adults can also set an example, she said. “All of us use screens, so it’s important to guide kids, teens and young adults to healthy screen use in a way that grows with them. As a parent, you can model healthy screen use – when to put it away, how to use it, how to avoid multitasking. And as kids get a little older, be more explicit, narrating why you put away your devices during dinner or other times together.
“Make sure they know how to entertain and soothe themselves without a screen and can handle being bored! Boredom breeds brilliance and creativity, so don’t be bothered when your kids complain they’re bored. Loneliness and discomfort will happen throughout life, so those are opportunities to support and mentor your kids in healthy ways to respond that don’t involve scrolling.”
