Danish researchers report that greater recreational screen use among youth is associated with higher cardiometabolic risk — including markers such as high blood pressure and insulin resistance — with the link strongest among those who sleep less. Based on data from more than 1,000 participants, the authors and outside experts say trimming discretionary screen time and improving sleep may help protect long‑term heart health.
A study published in the Journal of the American Heart Association found that more time on TVs, phones, tablets, computers and gaming systems during childhood and adolescence was linked to higher cardiometabolic risk. The research analyzed two Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) cohorts: COPSAC2010, assessed at ages 6 and 10, and COPSAC2000, assessed at age 18.
Researchers reported screen use for 657 children at age 6 and 630 at age 10 in COPSAC2010, where average leisure screen time rose from about 2.0 hours per day at age 6 to 3.2 hours at age 10. In COPSAC2000, 364 adolescents reported an average of 6.1 hours per day at age 18. Screen time covered TV/movies, gaming and other device use for fun. Parents reported screen time for children, while adolescents provided their own reports. Sleep was measured with sensors over a two‑week period.
To capture overall risk, investigators created a composite cardiometabolic score from waist circumference, blood pressure, high‑density lipoprotein (HDL) cholesterol, triglycerides and glucose, adjusted for sex and age. Each additional hour of recreational screen time corresponded to a 0.08 standard‑deviation increase in the cardiometabolic score at age 10 and a 0.13 increase at age 18. As lead author David Horner, M.D., PhD., noted, that means three extra hours a day translates to roughly a quarter to half a standard‑deviation higher risk than peers.
Shorter sleep amplified the association. In childhood, sleep duration not only moderated but also partially explained the link: about 12% of the screen time–risk relationship was mediated by shorter sleep. Later bedtimes also strengthened the association, particularly in adolescence. Using machine‑learning analyses of blood samples, the team identified a metabolomic “screen‑time fingerprint,” and higher screen time in adolescence was tied to higher predicted adult cardiovascular risk.
“Limiting discretionary screen time in childhood and adolescence may protect long‑term heart and metabolic health,” Horner said. Amanda Marma Perak, M.D., M.S.C.I., FAHA — who was not involved in the research — advised families to start with sleep: moving screen use earlier and prioritizing earlier, longer sleep, while adults model healthy screen habits for kids.
The authors emphasized that the study is observational and cannot prove causation. Screen exposure was self‑ or parent‑reported, which can introduce measurement error. They suggest future trials test whether reducing screen use, particularly before bedtime, lowers cardiometabolic risk.