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The average kid between 8 and 11 uses screens for more than three-and-a-half hours per day.
- The vast majority of kids don't meet recommended guidelines for sleep, exercise, and screen use, according to a new study, and almost 30% meet none of those guidelines.
- Kids should get between nine and 11 hours of sleep a night, should limit recreational screen use to two hours per day, and should get at least an hour of moderate-to-vigorous exercise, according to the Canadian 24-Hour Movement Guidelines for Children and Youth.
- The better kids in the US do on those guidelines, the better they perform on cognitive tests, according to the study.
Kids need balance when it comes to how they spend their time. They also need sleep. Most don't get enough of either, according to a study published September 27 in the journal The Lancet Child & Adolescent Health.
Children between ages five and 13 should get nine to 11 hours of sleep per night, at least an hour of moderate-to-vigorous exercise each day, and shouldn't use screens recreationally for more than two hours per day, according to the Canadian 24-Hour Movement Guidelines for Children and Youth.
But only 5% of US children aged eight to 11 meet all three of those recommendations, according to the new study - and over a quarter of kids that age don't meet any of them.
The more of those guidelines kids meet, the better they do on tests of global cognition, which can function as a measure of intelligence or a surrogate for IQ, lead study author Jeremy Walsh of the CHEO Research Institute said on a Lancet podcast about the study.
Walsh and co-authors say this research shows the importance of setting limits for sleep and screen time for kids.
"Consistently, for child health, the whole day matters," Walsh said on the podcast. "We know that children who have excessive screen time before bed have worse sleep and that sleep-deprived children are less active. And during those periods of less activity, children might be having more pursuits like excessive screen time."
If parents can regulate screen time, that might help kids get more sleep, which could help them be more active - and the same sorts of interactions could occur by trying to enforce bedtimes and activity levels.
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Some screen use is okay, but experts say setting some limits is helpful.
Tracking sleep, screen, and activity for thousands of kids
The authors of the new study used data from the ongoing ABCD Study, which is following more than 10,000 kids for 10 years to revolutionize our understanding of child development.
For this research, the team looked at data from 4,520 children aged 8 to 11 from 20 locations across the US. Kids and parents completed questionnaires to measure sleep time, screen time, and physical activity.
The cognitive tests they took measured language abilities, episodic memory, executive function, attention, working memory and processing speed.
Kids did best on the sleep measures - about half got nine to 11 hours a night. Only 37% limited recreational screen time to two hours a day, and kids averaged more than three-and-a-half hours per day of recreational screen time, which includes TV, mobile device use, and video games. A dismal 18% of the kids got enough physical activity.
The measures that had the strongest links to cognitive scores were screen time and sleep, though Walsh said a more accurate way of looking of exercise might reveal definitive links on that measure as well. But all in all, the authors concluded that since so few kids met all three measures (and some didn't meet a single one) improving adherence to any of these guidelines could potentially improve physical health and cognitive performance.
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Kids need to get enough sleep and exercise.
There's still much to be learned
Since this was an observational study, no one knows for sure that meeting these recommended guidelines would cause an improvement in cognitive performance - just that the kids who meet the requirements also do better on these cognitive tests.
As Anya Kamenetz, author of "The Art of Screen Time!", said on Twitter, the study "primarily tells us that parents who follow expert recommendations have kids who do well on tests."
The benefits of getting enough sleep are well-documented, but screen time is more complex. It's hard to know how different forms of screen use affect cognition or mental health. Video games may not have the same effect as television, educational content may have different effects than other forms of entertainment, and smartphones and social media may have a host of different effects, both positive and negative.
Our understanding of the effects of "screen time" on cognition or health in general may eventually become more nuanced.
Still, the overall takeaway is one that's still probably safe to apply to kids - and adults as well.
Stay active, get enough exercise and sleep, and allow for some screen time, but put checks on excessive use.