Sedentary living can have serious health consequences. Obesity and the health consequences of this condition, including heart disease, are strongly correlated with sedentary lifestyles. Diabetes and cognitive impairment in later life are also associated with a sedentary lifestyle.
New research suggests that more screen time for kids ages 9-11 leads to a sedentary lifestyle — and correlated with heart disease in adulthood. A study of 5,844 children in a dozen different countries found that the average amount of sedentary time each day was close to 9 hours. Kids who spent more time sitting weighed more, got less physical activity than the recommended amount, and generally spent more than two hours per day on screen time.
Another study followed 14,500 babies until age 24. The subjects were tested at ages 11, 15, and 24 to see how much time they spent sitting. Those who were more sedentary — and again much of the sedentary time was spent with screens — had increased heart weight, putting them at risk for cardiac health problems. While the subjects became more sedentary as they got older, those who were more sedentary at 11 generally kept those habits and were still more sedentary at 24.
A third study examined 200,615 adolescents from 39 different countries, asking whether more screen time led to more sedentary lifestyles. While some European countries did not show an association between more screen time and less active play, the North American countries showed a strong correlation. Kids who spent more than two hours a day with TV or video games spent about half an hour less each week in active play.
These studies, and others like them, show that more screen time usually means more sitting for kids, and that more sitting for kids usually means a more sedentary way of life when they grow up.
What’s too much screen time? Experts agree that two hours a day is the upper limit for tweens and teens, yet a 2020 survey found that the average American boy spent three hours a day playing video games and another three hours watching TV.
These research results reinforce the importance of limiting screen time. For kids in the tween age group, two hours a day should be the upper limit. The American Academy of Child and Adolescent Psychiatry has a long list of negative outcomes associated with too much screen time, and the connection with poor heart health is just one more reason to work on limiting that time.
The highest amount of sedentary time was found among kids who had a TV or computer in their bedrooms. If you worry that your kids are spending too much screen time, avoiding the private TV or game console in their bedroom can be a simple fix.
The data from Eastern Europe and the Mediterranean suggest that putting a high value on physical activity can help kids maintain more active lifestyles even if they spend a lot of time playing video games or watching TV. Developing a habit of family bike rides, hiking, or playing outdoor games could help kids avoid the sedentary habits that could threaten their health as they grow up.