Originally published Aug. 13, 2021 by the Ottawa Citizen.

By Andrew Duffy

A large, international study that involved more than half a million teenagers has distilled a clear, simple formula for the improved mental wellbeing of adolescents: more exercise and less screen time.

Published earlier this week in The Lancet Child and Adolescent Health, the study was the product of a collaboration between Dr. Mark Tremblay, a senior scientist at the CHEO Research Institute, and Australia’s Dr. Asad Khan, of the University of Queensland.


The researchers found that mental wellbeing declined when adolescents (13 to 15 years old) indulged in more than two hours of recreational screen time a day.

“The greater the screen time, the greater the symptoms,” said Dr. Tremblay, president of the Active Healthy Kids Global Alliance.

The researchers also found a direct relationship between exercise and wellbeing: Teenagers’ sense of mental wellbeing improved with each additional day that they did at least one hour of exercise.

“If you can do one day, it improves. If you can do two, your mental wellbeing improves more, and so on,” said Tremblay, a professor in the faculty of medicine at the University of Ottawa.

The study’s findings, he said, are particularly relevant during the pandemic, which has isolated many teens, reduced their opportunities for exercise, and increased the amount of time they spend online.

CHEO has reported a 50 percent increase in emergency assessments for eating disorders during the pandemic, and local pediatricians have reported a surge in mental health issues among their patients.

Tremblay said the paper’s findings, repeated in country after country, underline the importance of decreasing screen time and increasing physical activity for both boys and girls.

“It’s time that we take this seriously,” he said. “The fact that we’re, hopefully, coming out of the pandemic gives us the chance to say, ‘OK we’ve got to recalibrate here anyway.’ Let’s learn to regulate this in a way that’s more consistent with healthy living.”

The new study – the largest of its kind – examined data from more than 577,000 adolescents living in 42 North American and European countries. The data was drawn from cross-sectional surveys conducted before the pandemic in 2006, 2010 and 2014.

As part of the surveys, participants assessed their own physical activity and recreational screen time, including television, YouTube, gaming and social media. They also described how happy they felt about their lives on a scale of one to 10, and indicated the frequency with which they suffered from irritability, sleep problems, headaches and other problems.

Boys reported a slightly higher life satisfaction score (7.7) than girls (7.5) even though they spent more time on their screens. Boys spent an average of 6.3 hours on screens a day while girls reported an average of 5.4 hours on electronic devices.

Boys were also much more likely to report that they were physically active every day (23.6 percent) than girls (14.3 percent).

Among those surveyed, the greatest life satisfaction was reported by boys who had between one and two hours of screen time a day and physical activity seven days a week. Among girls, the highest levels of satisfaction were reported by those with less than one hour of screen time a day and daily physical activity.

Those who engaged in no physical activity reported the lowest life satisfaction levels.

The researchers concluded: “Our findings provide support for the current recreational screen time recommendation of two hours or less per day, and the physical activity recommendation of 60 minutes or more per day for health and wellbeing.”

Interestingly, the researchers found that wellbeing could be improved by increasing physical activity levels even among those teenagers who engaged in unusually high amounts of screen time. Among adolescents reporting more than eight hours of screen time per day, significant increases in life satisfaction were seen for each additional day that an individual was physically active.

“We know that a high screen time isn’t a profile that’s ideal for mental wellbeing,” Tremblay said, “but you can help to mitigate it by being physically active.”

Tremblay said parents can help by setting limits on when phones and other devices are used, and by modelling the importance of physical activity and other recreational pursuits that don’t involve a screen.

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    A new study highlights the power of exercise to improve the mental well-being of teenagers, even those who spend too much time on phones and other devices.
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