Key TakeawaysScreen time appears to increase risk of future heart health problems among children and teensEach extra hour of screen time increases the level of risk factors associated with heart diseaseLack of sleep magnifies this effect.WEDNESDAY, Aug. 6, 2025 (HealthDay News) — The time children and teens spend video gaming, scrolling through social media or watching TV could be putting their future heart health at risk, a new study says.Each additional hour of screen time is associated with an increase in heart risk factors like blood pressure, cholesterol and blood sugar levels, researchers reported today in the Journal of the American Heart Association.“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,” lead investigator David Horner, a researcher at the University of Copenhagen in Denmark, said in a news release.“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,” Horner added.For the study, researchers pooled data from more than 1,000 participants in two Danish studies of childhood health.Each child received a heart health risk score based on factors like waist size, blood pressure, “good” HDL cholesterol, triglycerides and blood sugar, researchers said. Parents reported on the kids’ screen time.Every hour a child or teen spent glued to a screen caused those risk factors to tilt toward the bad, results showed.A child’s sleep patterns contributed to this risk, researchers added.Both shorter sleep duration and hitting the sack later intensified the relationship between screen time and heart health risk, results show. Kids and teens who had less sleep showed significantly higher risk associated with the same amount of screen time.“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.”An artificial intelligence (AI) analysis found that kids’ blood carried a set of markers – what researchers called a “screen-time fingerprint” – that could predict how much time they’d been spending with screens, researchers added.“We 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,” Horner said. “This suggests that screen-related metabolic changes may carry early signals of long-term heart health risk.”Since this was an observational study, the research cannot prove a direct cause-and-effect relationship between screen time and heart health, researchers noted.Nevertheless, pediatricians should consider a discussion of children’s screen habits during regular check-ups, Horner said.The results also highlight the importance of good sleep to a child’s health, said Dr. Amanda Marma Perak, chair of the American Heart Association’s Young Hearts Cardiovascular Disease Prevention Committee. Perak, who was not involved in this research, reviewed the findings.“If cutting back on screen time feels difficult, start by moving screen time earlier and focusing on getting into bed earlier and for longer,” said Perak, an assistant professor of pediatrics and preventive medicine at Northwestern University Feinberg School of Medicine in Chicago.Parents also should be prepared to set a good example, she added in a news release.“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,” Perak said. “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.”It's also important to teach kids how to entertain themselves without a screen, and to handle the discomfort that comes with boredom, Perak said.“Boredom breeds brilliance and creativity, so don’t be bothered when your kids complain they’re bored,” Perak said. “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.”More informationJohns Hopkins Medicine has more on the effects of screen time on children.SOURCE: American Heart Association, news release, Aug. 6, 2025 .What This Means For YouParents should monitor their children’s screen time and make sure they aren’t spending too much time on their computer, smartphone, tablet or TV..Sign up for our weekly HealthDay newsletter