Checking a smartphone. — Image by © Tim Sandle

More time using electronic devices or watching TV among children and young adults was linked with higher cardiometabolic disease risk, including high blood pressure, high cholesterol and insulin resistance.

The implication is that too much screen time, especially when in your youth, may set the stage for future heart and metabolic diseases. This is particularly when combined with insufficient sleep.

This is the finding of Danish researchers who discovered a measurable rise in cardiometabolic risk scores and a metabolic “fingerprint” in frequent screen users.

The study

Scientists analysed two groups: one of 10-year-olds followed in 2010 and one of 18-year-olds followed in 2000. They examined how leisure screen use related to cardiometabolic risk factors. Screen time included watching TV and movies, gaming and time on phones, tablets or computers for fun.

To capture overall risk, researchers created a composite cardiometabolic score based on multiple components of metabolic syndrome, including waist size, blood pressure, high-density lipoprotein “good” cholesterol, triglycerides and blood sugar levels. They adjusted for sex and age. The derived score reflected each participant’s risk relative to the study average (in standard deviations): 0 indicates average risk, and 1 indicates one standard deviation above average.

Results

The analysis showed that every additional hour of recreational screen time was linked with an increase of about 0.08 standard deviations in the cardiometabolic score for the 10-year-olds and 0.13 standard deviations for the 18-year-olds.

This means 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.

While this is a small change per hour, when screen time accumulates to three, five or even six hours a day, there is a cumulative effect.

In addition, short sleep and later bedtimes strengthened the relationship between screen time and cardiometabolic risk. Youth who slept less showed a notably higher risk linked to the same amount of screen exposure.

In a machine learning analysis, investigators identified a distinctive pattern of blood metabolites that appeared to correlate with screen time.

Limitations of the study

It should be noted that the study was observational, therefore it reveals associations rather than direct cause and effect. In addition, screen use for the 10-year-olds and 18-year-olds was reported by parents through questionnaires, which may not perfectly reflect actual time spent on screens.

Supporting findings

A 2023 scientific statement from the American Heart Association reported that “cardiometabolic risk is accruing at younger and younger ages,” and that only 29% of U.S. youth ages 2 to 19 had favourable cardiometabolic health in 2013-2018 National Health and Nutrition Examination Survey data.

Recommendations

The researchers conclude that better sleep and balanced daily routines can help offset these effects and safeguard lifelong health.

The research appears in the Journal of the American Heart Association, titled “Screen Time Is Associated With Cardiometabolic and Cardiovascular Disease Risk in Childhood and Adolescence.”