Every hour spent in front of a screen increases heart risks in young people

The researchers analyzed data from more than 1,000 participants from two Danish cohorts: a group of 10-year-olds studied in 2010 and a group of 18-year-olds studied in 2000. Screen time included time spent watching television, playing video games, or using phones, tablets, or computers for leisure.

The researchers developed a score based on a set of metabolic syndrome components—waist circumference, blood pressure, good and bad cholesterol levels—that they adjusted for sex and age. This cardiometabolic score reflected the participant's overall risk compared to a control group: 0 corresponding to no risk and 1 to an above-average risk.

The analysis found that each additional hour of screen time increased the cardiometabolic score by approximately 0.08 standard deviations in 10-year-olds and 0.13 standard deviations in 18-year-olds.

Which, at first glance, may seem trivial. “It’s a small change,” acknowledges Dr. Horner. “But when screen time accumulates to three, five, or even six hours a day, as we’ve seen in many adolescents, it adds up. A child with three additional hours of screen time a day is already at greater risk than their peers.”

Sleep, an aggravating factor

The study also found that sleep duration and bedtime affected the relationship between screen time and cardiometabolic risk. Screen time often leads to shorter sleep and later bedtimes, thus exacerbating the risks associated with screen time.

Dr. Amanda Marma Perak, chair of the American Heart Association's Committee on Cardiovascular Disease Prevention, emphasizes that adults should lead by example. "We all use screens, so it's important to coach children, teens, and young adults toward healthy screen use that's appropriate for their growth. As a parent, you can model healthy screen use: when to put them away, how to use them... And as kids get older, be more explicit about why you put your devices away during dinner..."

Pediatric cancer: patients at higher risk of cancer and cardiovascular disease in adulthood