This Habit May Raise Heart Disease Risk in Kids

Heart disease is a major global health issue, and it can even make an impact in childhood. Certain factors, like insulin resistance and inflammation, are linked to the risk of developing it early. These risks may be worsening as kids and teens spend more time on screens for school, entertainment and socializing. Screen time can lead to less sleep, more sitting, less exercise and unhealthy eating habits, all of which contribute to these problems.

This is especially concerning because studies show that teens with high screen time are more likely to face obesity, larger waistlines and diabetes as adults. However, many of these studies rely on self-reported habits like diet, sleep and exercise, which can sometimes be inaccurate. To help bridge our knowledge gap, researchers set out to better understand how screen time affects health by looking at two groups of mothers and children over time.

These groups are part of the COPSAC (Copenhagen Prospective Studies on Asthma in Childhood) research, which allowed researchers to track how screen time habits and their impact on health change from childhood to adolescence, and the results were published in the Journal of the American Heart Association.

How Was The Study Conducted?

This study used two groups of mothers and children from the Copenhagen Prospective Studies on Asthma in Childhood cohort to explore the relationship between screen time and health. The first group, COPSAC2010, included 700 mother-child pairs from the general population, with detailed health data collected from birth to age 10. The second group, COPSAC2000, included 411 children born to mothers with asthma, with data collected from birth to age 18. 

To ensure accurate results, participants with type 1 diabetes were excluded, as this condition could affect the findings. Screen time was measured through questionnaires, with parents reporting children’s screen habits in COPSAC2010 and teens self-reporting in COPSAC2000. Total screen time was calculated based on weekday and weekend use.

The study focused on cardiometabolic risk (CMR), which includes factors like waist circumference, systolic blood pressure, high‐density lipoprotein cholesterol, triglycerides and glucose. These were combined into a CMR score, adjusted for age, sex, and other factors. Additional health measures, such as insulin resistance, inflammation markers and body composition (fat, muscle and bone mass), were also analyzed. 

Advanced blood tests and a cardiovascular risk score, based on data from a large adult study, were used to link screen time to future heart disease risks. Physical activity and sleep were tracked using wearable devices, which measured movement, sedentary time and sleep patterns. The analysis also considered factors like family income, maternal education, smoking during pregnancy and puberty markers to ensure a comprehensive understanding of how screen time impacts health.

What Did The Study Find?

In the first group, after accounting for other factors, researchers found that for every additional hour of screen time, there was a small but significant increase in overall cardiometabolic risk. The effect was stronger in boys (0.10 increase) compared to girls (0.02 increase), though the difference between boys and girls wasn’t statistically significant.

The link between screen time and cardiometabolic risk was more noticeable at age 10 than at age 6. At age 10, each extra hour of screen time was associated with a 0.16 increase in cardiometabolic risk, while at age 6, the increase was smaller and not statistically significant. 

Adjusting for prenatal interventions, like omega-3 supplements and high-dose vitamin D, did not change these findings, showing that the association between screen time and CMR remained consistent. Findings also showed that for every additional hour of screen time during this period, there was a small but significant increase in insulin resistance. And the relationship between cardiometabolic risk and screen time only grew over time—the connection between screen time and a higher CMR score was stronger at age 10 than age 6.

In the COPSAC2000 study, researchers found that at age 18, more screen time was strongly linked to higher cardiometabolic risk (CMR). For every additional hour of screen time, the overall CMR score increased by 0.13. Specific health factors were also significantly affected: waist circumference increased by 1.30 cm, systolic blood pressure rose by 0.63 mmHg, HDL cholesterol decreased slightly and markers of inflammation and cholesterol both increased slightly.

When looking at boys and girls separately, the effect of extended screen time appeared stronger in boys. 

The study also looked at how lifestyle factors, like sleep, activity and diet, influenced the relationship between screen time and CMR. Sleep emerged as a key factor. In COPSAC2010, the negative effects of screen time on CMR were worse when children slept less or went to bed later. This pattern was also seen in COPSAC2000, where less sleep significantly worsened the impact of screen time on CMR. These findings highlight the importance of healthy sleep habits in reducing the harmful effects of screen time on heart and metabolic health.

This study has some limitations that are important to understand. First, because it’s observational, we can’t say for sure that screen time directly causes the health effects observed, as other factors the researchers didn’t measure could also play a role. Additionally, the researchers relied on participants or parents reporting screen time, which might not always be accurate. For example, people might forget details or report what they think is expected. 

While this method is common in research, future studies could improve accuracy by using tools like apps or devices to track screen time more precisely, including details like the type of device, how long it’s used, and when during the day.

Another limitation is that while the researchers used objective tools to measure things like sleep and physical activity, the data on diet was self-reported. This means people might not remember everything they ate or might report healthier habits than they actually have. Lastly, some parts of the analysis, like exploring how sleep influences the relationship between screen time and health, were more experimental. These findings are useful for generating new ideas but shouldn’t be taken as final proof. And while the researchers noticed stronger effects in boys, the differences between boys and girls weren’t always statistically significant, so more research is needed to confirm these patterns.

How Does This Apply To Real Life?

In today’s digital world, screens are a big part of daily life for kids and teens. But this research shows that spending too much time on screens is linked to health consequences, including an increased risk of insulin resistance, higher blood pressure and larger waistlines, which are all factors that can lead to heart disease later in life. 

While the results didn’t specify a specific screen time limit to help mitigate risks, the message is clear: less screen time is better for long-term health. Even small changes, like cutting back an hour or two a day, may help reduce these risks and promote healthier habits.

Finding balance is key. Encouraging kids to take breaks from screens, get moving and stick to regular sleep schedules can make a big difference. Sleep, in particular, plays a crucial role; this study found that less sleep or later bedtimes can make the negative effects of screen time even worse. By setting limits on screen use and prioritizing activities like outdoor play, family meals and consistent bedtimes, parents and caregivers can help protect their children’s health while still allowing room for the benefits of technology.

Our Expert Take

This research published in the Journal of the American Heart Association sheds light on the growing concern of how screen time impacts children’s and teens’ health. By studying two groups of kids over time, researchers found that more screen time was linked to higher risks of factors that can contribute to heart disease later in life. The effects were stronger in boys and worsened when kids had less sleep or went to bed later. While the study didn’t provide a specific screen time limit, it clearly suggests that reducing screen time, even by a little bit, could help lower these risks and support healthier habits.

Finding a balance between screen use and other activities is key. Encouraging kids to take breaks from screens, stay active and maintain consistent sleep schedules can go a long way in protecting their health. Sleep, in particular, may play a critical role in reducing the negative effects of screen time.