Kids and teens who spend more time on screens and get less sleep may have higher risks for future heart and metabolic problems such as high blood pressure, high blood sugar, unhealthy cholesterol levels and excess belly fat, according to a new study published in the Journal of the American Heart Association.
The study collected data on self-reported or parent-reported screen time and sleep hours for over 1,000 kids and teenagers living in Denmark. Screen time included either watching TV or using electronic devices. Cardiometabolic health data measured cholesterol levels, blood sugar levels, waist measurements, blood pressure and insulin resistance.
Each additional hour of screen time was associated with higher cardiometabolic risk for both kids and teenagers. Teenagers with excess screen time were especially at risk. Additionally, the risk was heightened for kids and teenagers reporting fewer hours of sleep.
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"This study helps bolster our confidence in the finding that screen time in youth can adversely impact cardiometabolic health," Dr. Amanda Marma Perak, chair of the American Heart Association's Young Hearts Cardiovascular Disease Prevention Committee, and an assistant professor of pediatrics and preventive medicine at Northwestern University Feinberg School of Medicine in Chicago, wrote in a statement to ABC news.
Previous long-term studies have confirmed a link between cardiovascular disease in adulthood and higher screen time in teens. But this is the first study that looked at associations between cardiometabolic risk and screen time for both kids and teens, Perak noted.
However, this does not imply that excess screen time directly affects cardiovascular health.
"This was still an observational study showing correlation rather than an experiment showing causation," Perak wrote.
Another limitation of the study was a lack of distinguishing between screen time used for educational purposes versus more passive screen time like scrolling through social media or texting with friends.
"Other studies have suggested that it's the more passive screen time -- like watching TV for older generations, and scrolling social media for today's youth -- that is probably most detrimental, Perak wrote. "On the other hand, more active screen use -- like looking up new information, creating things (like videos or online illustrated books), or communicating (like FaceTime) with friends and family -- may not adversely impact heart health."
The study highlights the importance of jointly considering screen time and sleep patterns for promoting cardiovascular health in kids and teens.
Perak pointed out that youth who spend more time glued to their screens tend to have worse heart health.
"And secondarily, the combination of more time on screens plus going to bed late and/or not getting enough sleep appears to be more harmful for heart health," she wrote.
Perak added that she'd like to see more studies to understand the impact screen time may have on long-term cardiovascular health in more diverse populations.
Dr. Jennifer Miao is a board-certified cardiologist, critical care and interventional cardiology fellow at Yale School of Medicine/YNHH, and a fellow with the ABC News' Medical Unit.
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