Study links excess screen time in children to higher heart and metabolic risk
They analysed data from over 1,000 participants across two long-term Danish cohorts, including children aged 10 and adolescents aged 18, to investigate the link between screen habits and heart and metabolic health.
Children and teenagers who spend long hours on phones, tablets, televisions and other screens are at increased risk of developing heart and metabolic problems later in life, especially when they do not get enough sleep, a new study has warned.
Researchers found that even an additional hour of daily screen time can raise cardiometabolic risk, with the effects intensified by shorter sleep duration.
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The study, published in the Journal of the American Heart Association, was conducted by researchers from the University of Copenhagen’s Copenhagen Prospective Studies on Asthma in Childhood (COPSAC).
They analysed data from over 1,000 participants across two long-term Danish cohorts, including children aged 10 and adolescents aged 18, to investigate the link between screen habits and heart and metabolic health.
The findings revealed that each extra hour of recreational screen time was associated with a measurable increase in cardiometabolic risk. Among 10-year-olds, the increase was 0.08 standard deviations per hour, while among 18-year-olds it 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,” lead author David Horner, a researcher at COPSAC, said.
“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 incorporating indicators such as waist circumference, blood pressure, HDL (“good”) cholesterol, triglycerides and blood sugar levels.
Using machine learning, they also identified a unique blood metabolite pattern they described as a “screen-time fingerprint”, suggesting that prolonged screen use may trigger biological changes even in childhood.
The study showed that the combination of high screen time and insufficient sleep significantly increased risk scores.
“In childhood, sleep duration not only moderated the relationship but also explained about 12 per cent of it. This suggests that shorter sleep partly mediates how screen time contributes to metabolic changes,” Horner said.
Researchers highlighted that screen use among adolescents often reaches five to six hours daily, which may silently influence long-term health outcomes.
“Limiting discretionary screen time in childhood and adolescence may protect long-term heart and metabolic health,” Dr Horner said.
Experts recommend incorporating discussions of screen habits into routine pediatric care alongside diet and exercise advice.
American Heart Association Young Hearts Cardiovascular Disease Prevention Committee chairperson Amanda Perak urged families to approach changes gradually.
“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 added that parents play a key role in guiding children. “All of us use screens, so it’s important to model healthy, mindful usage. Put devices away during meals, explain why, and encourage screen-free family time,” Perak said.
Researchers also noted sex differences, with boys generally showing stronger associations between screen time and risk factors, though formal interaction tests did not show statistically significant differences.
Using advanced blood metabolomics, the researchers identified 37 biomarkers associated with screen time, many linked to lipid metabolism and obesity-related traits.
“This suggests that increased screen time may be associated with early alterations in lipid transport and fatty acid balance, providing a mechanistic insight into the observed cardiometabolic risk,” Horner explained.
The research also examined how lifestyle factors, particularly sleep, influenced the relationship between screen time and cardiometabolic risk. Shorter sleep duration and later sleep onset were found to worsen the impact of screen use on heart and metabolic health.
The study is among the first to use long-term mother-child cohort data, machine learning and adult-trained cardiovascular risk scores to assess the impact of screen time on early-life cardiometabolic health.
While the research is observational and cannot definitively prove causation, it suggests that screen time should be considered an independent behavioural risk factor for early metabolic and cardiovascular changes.
The study emphasises that cardiometabolic risk can start accumulating early, with lifestyle factors such as sleep duration and bedtime timing significantly influencing the impact of screen use.
Researchers emphasised that interventions to reduce risk may need to be tailored differently for children and adolescents, considering these varying influences.
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