If your child or teen is spending hours scrolling TikTok or gaming into the night, a new study suggests it might be doing more than just messing with their sleep, it could be quietly putting their heart health at risk.

According to a new research study, published Journal of the American Heart Association, high amounts of recreational screen time among youth, whether from phones, computers, TVs, or gaming consoles, may be linked to an increased risk of cardiometabolic diseases. These include conditions like high blood pressure, high cholesterol, and even insulin resistance.

Researchers at the University of Copenhagen dug into data from over 1,000 children and teens as part of two long-running health studies. What they found was concerning. The more time kids spent on screens, the higher their risk of developing early signs of heart and metabolic problems.

“Limiting discretionary screen time in childhood and adolescence may protect long-term heart and metabolic health,” Dr. David Horner, lead author of the study and researcher at Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) said in a recent press release. “Our study provides evidence that this connection starts early and highlights the importance of having balanced daily routines.”

The research measured a cardiometabolic “score” based on waist size, blood pressure, cholesterol, blood sugar, and other health markers. For each extra hour of screen time, a child’s score went up, by 0.08 standard deviations at age 10, and 0.13 at age 18. That might sound small, but it adds up fast.

“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 explained. “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.”

The study also found a major link between screen use and sleep habits, specifically that less sleep or going to bed later made the health risks from screen time even worse.

“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.”

The researchers even discovered a “screen-time fingerprint” in the blood, a set of changes in metabolites that appear to reflect long-term biological impact from high screen use.

What can parents do to help turn things around? Well, there are simple ways to start creating healthier habits, starting with sleep.

“If cutting back on screen time feels difficult, start by moving screentime earlier and focusing on getting into bed earlier and for longer,” advised Dr. Amanda Marma Perak, chair of the American Heart Association’s Young Hearts Cardiovascular Disease Prevention Committee.

“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.”

Her biggest tip? Let kids be bored. “Boredom breeds brilliance and creativity, so don’t be bothered when your kids complain they’re bored.”

The researchers note that while this study is observational (meaning it can’t prove cause and effect), the associations are strong enough to consider screen time as part of regular health conversations with kids, right alongside diet, exercise, and sleep.