The study assessed the behavior of 4,500 children, ages 8 to 11, by looking at their sleep schedules, how much time they spent on screens and their amount of exercise, and analyzed how those factors affected the children’s mental abilities.
The researchers compared the results with national guidelines for children’s health. The guidelines recommend that children in that age group get at least an hour of physical activity and no more than two hours of recreational screen time a day and nine to 11 hours of sleep each night.
The researchers found that only five percent of children met all three recommendations. Sixty-three percent of children spent more than two hours a day staring at screens, failing to meet the screen-time limit.
Children who did not meet all three criteria performed worse on thinking, language and memory tests than kids who met the recommendations, according to the study. But reduced screen time was positively linked to superior mental performance, the study found.
“We need to pay attention to how long we are on the screens for,” said Jeremy Walsh, a postdoctoral fellow at the University of British Columbia and the lead author of the study. “This study is showing that less than two hours of recreational screen time is beneficial for children.”
“These findings highlight the importance of limiting recreational screen time and encouraging healthy sleep to improve cognition in children,” the study’s authors wrote.
The findings arrive as technology companies take steps to address worries over increased use of devices such as mobile phones. In recent months, parents, consumers and technologists have called for more discussion about young people and tech addiction and whether use of such devices could harm childhood development. Apple recently released advanced parental controls and unveiled a new control system that lets users monitor how much they’re using their iPhones. Google has also introduced new features to limit screen time and monitor use on Android devices.
While the observational study showed an association between reduced screen time and children’s higher mental performance, it did not establish a causal link, according to the BBC. The study’s authors said more research is needed to probe the links between screen time and cognition, including differentiating among the types of screen activities and what effects each has on children.
The study drew from data that’s part of a larger, long-term research project on brain development and child health in the United States. The National Institutes of Health has funded researchers to track the biological and behavioral development of children through adolescence, showing how childhood experiences such as sports, sleep patterns, social media and video games influence a young person’s life.