Too much screen time could put kids’ hearts at risk

Excessive screen time might be doing more than just straining young eyes. A new study suggests it could also raise the risk of serious heart and metabolic problems later in life.

The researchers found that children and teens who spend more hours on recreational screen use – like watching TV, gaming, or scrolling on phones – tend to show higher signs of cardiometabolic risk.

That includes factors like higher blood pressure, elevated cholesterol, and insulin resistance.

Linking screen time to heart health

The scientists analyzed data from over 1,000 children and adolescents who took part in two long-running studies. The participants were either ten years old in 2010 or 18 years old in 2000.

The researchers measured screen time based on leisure activities such as TV, movies, video games, and personal devices.

They then compared that with a “cardiometabolic score.” This score is a composite measure of risk factors including waist size, blood pressure, cholesterol, triglycerides, and blood sugar. A score of zero meant average risk, while each additional “standard deviation” above zero indicated greater risk.

“Limiting discretionary screen time in childhood and adolescence may protect long-term heart and metabolic health,” said study lead author Dr. David Horner, 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.”

How much screen time matters

The research showed that every extra hour of screen time increased the cardiometabolic score by about 0.08 in 10-year-olds and 0.13 in 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,” explained Dr. Horner.

“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. Multiply that across a whole population of children, and you’re looking at a meaningful shift in early cardiometabolic risk.”

Sleep explains screen effects

The study also revealed that sleep plays a big role in the screen time–health connection. Kids who slept less, or stayed up later, had higher risks for the same amount of screen time.

“In childhood, sleep duration not only moderated this relationship but also partially explained it: about 12 percent of the association between screen time and cardiometabolic risk was mediated through shorter sleep duration,” said Dr. Horner.

“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 “fingerprint” in the blood

Machine learning identified a specific set of blood markers that may be tied to screen time.

“We were able to detect a set of blood-metabolite changes – a ‘screen-time fingerprint’ – validating the potential biological impact of screen time behavior,” said Dr. Horner.

Using the same metabolomics data, the researchers assessed how screen time influenced predicted cardiovascular risk in adulthood.

They found a positive trend in childhood and a significant association in adolescence. This suggests that screen-related metabolic changes may carry 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,” Horner said. “These results also open the door to using metabolomic signatures as early objective markers of lifestyle risk.”

Tackle nighttime screen use

Dr. Amanda Marma Perak, chair of the American Heart Association’s Young Hearts Cardiovascular Disease Prevention Committee, noted that one way to cut back is to focus on bedtime first.

“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, who was not involved in the study.

“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.”

Parents can model healthy screen use by showing when to put devices away, use them, and avoid multitasking. As children grow, it’s best to explain why you put away devices during dinner or other shared time, noted the researchers.

“Make sure they know how to entertain and soothe themselves without a screen and can handle being bored,” Perak said. “Boredom breeds brilliance and creativity, so don’t be bothered when your kids complain they’re bored.”

Further research is needed

The researchers emphasize that the study shows correlation, not direct cause and effect.

Since parents reported their children’s screen time, there’s also a chance that the actual hours spent may be under- or overestimated.

Still, Dr. Horner suggests future research could explore whether reducing screen use before bedtime might lower heart risk. Light from devices at night may interfere with sleep.

The full study was published in the journal Journal of the American Heart Association.

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