Most of us love screen time – adults and children alike – but how safe is it for kids? New research indicates that screen time may be linked to cardiometabolic and cardiovascular risk.
This study published in the Journal of the American Heart Association is an analysis of data from over 1,000 participants in the Copenhagen Prospective Studies on Asthma in Childhood cohorts of 10-year-olds from 2010 and 18-year-olds from 2020. Screen time assessments were reported by parents and covered TV, movies, gaming or using phones, tablets or computers for leisure
Study authors focused on developing cardiometabolic (CMR) risk scores based on metabolic syndrome components that included waist circumference, systolic blood pressure, HDL cholesterol, triglycerides, and glucose, adjusted for sex and age. Secondary outcomes such as insulin resistance, inflammation, atherogenic lipoproteins, and anthropometric measures were also assessed.
“We utilized supervised machine learning modelling of blood NMR metabolomics to identify a unique metabolic signature of screen time,” the study authors explained. They found that increased screen time “was significantly associated with CMR in children and adolescents, with each additional hour of screen time linked to a higher CMR z-score.”
Study lead author Dr. David Horner, a researcher at the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) at the University of Copenhagen in Denmark, explained that a child with three extra hours of screen time a day would have roughly a quarter to half a standard-deviation higher risk than their peers. Although the change per hour is small, he said that it accumulates with more and more screen time and across a population, it can represent a “meaningful shift in early cardiometabolic risk that could carry into adulthood.”
According to the American Academy of Child and Adolescent Psychiatry, children ages 8 to 18 in the U.S. spent seven and a half hours a day watching or using screens as of this June. U.S. Census Bureau data from 2021 found that tablet ownership was 22% higher in families with children than in households without children.
“While households with children (under 18 years old) had higher rates of computer ownership and internet subscription than those without children, one of the largest differences was for so-called tablets – wireless, notebook-sized computers with touchscreens,” said the bureau.
In 2023, a statement from the American Heart Association noted that CMR risk was “accruing at younger and younger ages.” It also said just 29% of American youth ages 2 to 19 years had favorable cardiometabolic health based, on 2013-2018 data from the National Health and Nutrition Examination Survey.
This May, Audacy also reported on a study published this March in the JAMA Network Open journal that found that daily screen use prior to bed was associated with a 33% higher prevalence of poor sleep quality and 7.64 fewer minutes of sleep on workdays. In February, we reported on another study published in the PLOS journal that indicated “negative and significant associations were generally found between screen time and language skills, which were in turn positively associated with shared reading times,” in children. Authors of that study noted that child screen use is “ubiquitous,” and that it increased during the COVID-19 pandemic.
Per the new study, sleep duration moderated the relationship between screen time and CMR risk for conditions such as high blood pressure, high cholesterol and insulin resistance. Youth who slept for fewer hours had the strongest CMR risk. That suggests “screen use may harm health by ‘stealing’ time from sleep,” researchers said, according to a press release from the American Heart Association.
Researchers also used machine learning analysis to identify “a unique metabolic signature in the blood,” that appeared to be associated with screen time, a “screen-time fingerprint” of sorts. Horner said that “validated the potential biological impact of the screen time behavior.”
So, what should parents do? Screens are becoming more embedded into everyday life for work, school, leisure and sometimes even completing simple tasks like ordering groceries. Even so, experts agree that there should be limits on screen use.
“Limiting discretionary screen time in childhood and adolescence may protect long-term heart and metabolic health,” said Horner. “Our study provides evidence that this connection starts early and highlights the importance of having balanced daily routines.”
He recommends that recognizing and discussing screen habits become a part of pediatric appointments and broader lifestyle counseling, similar to diet and physical activity and said further research could explore the use of screen time before bed and its impact on circadian rhythm. Dr. Amanda Marma Perak, chair of the American Heart Association’s Young Hearts Cardiovascular Disease Prevention Committee also recommends starting with getting enough sleep rather than cutting screen time.
“If cutting back on screen time feels difficult, start by moving screen time earlier and focusing on getting into bed earlier and for longer,” said Perak, who was not involved in the recent study. She is also assistant professor of pediatrics and preventive medicine at Northwestern University Feinberg School of Medicine in Chicago.
Perak said adults should set examples of healthy screen use for children. Additionally, she said they should allow kids to get bored sometimes.
“Make sure they know how to entertain and soothe themselves without a screen and can handle being bored! Boredom breeds brilliance and creativity, so don’t be bothered when your kids complain they’re bored,” said Perak. “Loneliness and discomfort will happen throughout life, so those are opportunities to support and mentor your kids in healthy ways to respond that don’t involve scrolling.”
The AACAP has some recommended guidelines for youth screen use as well. It suggests limiting screen use to video chatting with adults until 18 months, limiting use to watching educational programming with a caregiver between 18 and 24 months, limiting screen time to one hour on week days and three hours on weekend days per day for children ages 2 through 5. Furthermore, it recommends that screens be turned off during family meals and outings, that parents make use of parental controls, that they avoid using screens as a pacifier and that they turn off screens 30 to 60 minutes before bedtime.