Hilary Thomson sets strict limits on her children’s screen time: 15 to 20 minutes a day for her son, who is 11, and during the week, none at all for her 5-year-old twin girls and 8-year-old daughter.

And after days filled with after-school sports, such as baseball, gymnastics and horseback riding, sleep is a priority, too – about 11 hours a night for the younger two, and between nine and 10 hours for the older ones.

“They’re much happier when they’ve had a decent amount of sleep,” the Vancouver resident says.

It turns out they may be smarter as a result, too.

A study published on Wednesday found children who adhered to Canadian guidelines for limiting recreational screen time to less than two hours a day, and achieving adequate physical activity and sleep, had greater cognitive abilities than those who did not. That is, they performed better on measures such as language abilities, executive function, attention and memory.

The latest research, published in The Lancet Child & Adolescent Health, is part of a wider effort to understand how our daily habits impact the way we think, particularly at a critical stage of development.

“We know these behaviours have independent effects on health. But they also have effects on each other, and there is an integration of how the whole day matters,” says Jeremy Walsh, the lead author of the study and post-doctoral fellow at the University of British Columbia, Okanagan.

The Lancet study, conducted by Dr. Walsh and his colleagues at the Children’s Hospital of Eastern Ontario Research Institute in Ottawa, relied on data from a large, longitudinal U.S. study, called the Adolescent Brain Cognitive Development study, which allows outside researchers to access the data to maximize their use.

Dr. Walsh and his team found only 5 per cent of participants met all three recommendations for physical activity, screen time and sleep. Nearly 30 per cent of them met none of recommendations.

Yet, the researchers found that the more individual recommendations the children met, the better their cognition was.

It appears Canadian children don’t fare any better than their U.S. counterparts. In a national report card, released in June, the non-profit ParticipACTION gave Canadian children a “D+” for overall physical activity, reporting only 35 per cent were getting the recommended amount of activity per day. Only about 5 per cent of Canadian children, between the ages of five to 17, meet all of the Canadian 24-Hour Movement Guidelines, and about 30 per cent fail to meet any, says Leigh Vanderloo, an exercise scientist with ParticipACTION, an organization that promotes active living.

On the bright side, she says, “that’s 30 per cent of kids that have the potential to reap all these additional benefits if we can just get them moving a bit more, engaging in less screen time and ensuring that they’re getting adequate and good quality sleep every night.”

Dr. Vanderloo, who was not involved in the study, says one of the reasons children fail to meet the guidelines is their physical activity tends to plummet once they reach school age.

“Once they enter into the school system, the schools and child care are definitely highly recognized as sedentary and obesogenic [or obesity-promoting] environments,” she says, noting that when children are given the opportunity to move more during the school day, their focus and ability to learn tends to improve.

The Globe and Mail, September 26, 2018