Digital danger: Screens and poor sleep linked to rising heart disease risk

A new study has warned that excessive screen use, especially when combined with too little sleep, may increase the risk of developing heart and metabolic problems later in life.

The findings, published in the Journal of the American Heart Association, revealed that prolonged use of electronic devices such as televisions, phones, tablets, and gaming systems among young people is strongly associated with higher risks of cardiometabolic diseases including high blood pressure, unhealthy cholesterol levels, and insulin resistance.

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Researchers from the University of Copenhagen’s Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) analysed data from over 1,000 participants drawn from two long-term Danish studies, one group of 10-year-olds and another of 18-year-olds, to better understand how screen habits relate to heart and metabolic health.

They found that every extra hour of recreational screen time was linked to a measurable increase in cardiometabolic risk. Among 10-year-olds, each additional hour of daily screen use raised risk scores by about 0.08 standard deviations, while among 18-year-olds, the increase was 0.13 standard deviations.

“This means that a child spending three extra hours a day in front of a screen could have roughly a quarter to half a standard deviation higher risk than their peers,” said lead author David Horner, a researcher at COPSAC. 

Adulthood

“It might seem small per hour, but over time, and across a population, it adds up to a significant shift in early health risks that can follow into adulthood.”

The researchers developed a composite cardiometabolic score that incorporated several health indicators, including waist size, blood pressure, HDL (“good”) cholesterol, triglycerides, and blood sugar levels. They also used machine learning to identify distinctive blood metabolite patterns linked to screen exposure, what Dr Horner described as a “screen-time fingerprint.”

These chemical signatures suggest that screen habits may trigger biological changes even in childhood. The study further found a positive trend between screen time and predicted cardiovascular risk in adulthood, particularly among adolescents.

Notably, insufficient sleep appeared to amplify the effects of high screen time. Children and teens who spent long hours on screens and slept fewer hours had significantly higher risk scores.

“In childhood, sleep duration not only moderated the relationship but also explained about 12 per cent of it,” Dr Horner said. “This suggests that shorter sleep partly mediates how screen time contributes to metabolic changes.”

The researchers further warned that today’s widespread screen use, often reaching five to six hours per day in adolescents, could be silently shaping long-term health outcomes. 

“Limiting discretionary screen time in childhood and adolescence may protect long-term heart and metabolic health,” Dr Horner emphasised. “Our study shows that the connection starts early and highlights the need for balanced daily routines.”

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Experts also say that addressing screen habits should become part of paediatric check-ups, alongside discussions on diet and exercise.

Dr Amanda Perak, chair of the American Heart Association Young Hearts Cardiovascular Disease Prevention Committee, advises families to start small when cutting down on screens. “If reducing screen time feels overwhelming, begin by moving it earlier in the day and focusing on getting into bed earlier and for longer,” she said.

She adds that parents play a crucial role in setting examples: “All of us use screens, so it’s important to guide children and teens to use them in healthy, mindful ways. Model good behaviour, put your devices away during meals, explain why, and encourage screen-free family time.”

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