child screen

Stop Playing Fortnite, and Go to Bed

We know exercise, sleep and reduced screen time are good for kids. Now we have evidence that it leads to superior global cognition.


Move more. Sleep more. Spend less time staring at screens. We all know maintaining healthy habits is good for our physical and mental well-being. But for children and teens, getting enough movement, sleep, and screen-free time could have a lasting impact on cognitive development.

The Canadian 24-hour Movement Behaviour guidelines for 5-to-17-year-olds include three basic requirements for overall health and well-being: more than an hour of moderate to vigorous physical activity, less than two hours of recreational screen time per day, and nine to 11 hours of sleep per night.

Now, research from the CHEO Research Institute has found that children who meet these recommendations have superior global cognition – a measure of general intelligence that includes language ability, memory, attention, and task completion.

The analysis used data from the U.S. Adolescent Brain Cognitive Development (ABCD) study of over 4,500 kids aged 9 and 10. The researchers explored how cognitive ability related to each recommendation, in isolation and combination, and the results are surprising.

Most countries, and the World Health Organization, have recommendations for sleep and exercise. Canada is the first country to propose limits for time spent in front of a back-lit screen, yet it is this recommendation that has the strongest impact on cognition.

“When we looked at the ABCD data, we saw clearly that the whole day matters for children’s cognitive health,” says Jeremy Walsh, lead author of the study who is now based at University of British Columbia Okanagan.

“The greatest benefits for cognition were when children met the screen time plus sleep time recommendations or the screen time recommendations alone.”

Despite this, Walsh stresses the importance of a holistic approach, as the more recommendations a child met, the higher their cognition score. However, only half the children studied met the sleep recommendation, 36% met the screen time recommendation and only 17% met the physical activity recommendation, with only 5% meeting all three.

Canadian kids aren’t much better, with just 15% achieving all three.

For Walsh, the next step is to see how the ABCD cohort develops over the next 10 years and understand more about how the type of screen and type of content (educational versus entertainment) impacts cognition.

In the meantime, the study underscores the interconnected nature of physical activity, screen time, and sleep. Helping kids meet the recommendations for all three could help set them up for health and academic success.

‹ Previous post
Next post ›

Amy Noise is a science communicator who is fascinated by how and why the world works. Always learning, she is passionate about science and sharing it with the world to improve and protect our health, society and environment. Amy earned her BSc (biology and science communication) at the University of Manchester, and MSc (nutrition science and policy) at King’s College London, UK. She tweets sporadically @any_noise