Under the Hood

More Screen Time Could Make Children Less Smart

According to a new study, researchers found better mental ability among children — in the 8-11 age group —  who spent less than two hours a day using screen devices for fun.

The study titled "Associations between 24 hour movement behaviours and global cognition in US children: a cross-sectional observational study" was published in the Lancet Child & Adolescent Health journal on Sept. 26.

In order to ensure good cognitive development in children, the Canadian 24-hour Movement Guidelines provided the following recommendations — nine to eleven hours of sleep, less than two hours of recreational screen time, and at least one hour of physical activity on a daily basis.

Using screen devices for fun activities such as playing games or watching videos was referred to as recreational screen use. This, as well as sleep quality and levels of exercise, were known to independently impact the cognitive health of a child.

"However, these behaviors are never considered in combination," said Jeremy Walsh, lead author of the study and a former post-doctoral fellow at the Children's Hospital of Eastern Ontario. "We really had an opportunity here to look at how meeting each of these guidelines and meeting all of the guidelines relate to cognition in a large sample of American children."

As part of the study, 4,500 children in the United States were surveyed on the behaviors and were also assessed on their cognitive ability which included language, memory, processing speed, and attention. 

Overall, only 5 percent of the children in the study met all three recommendations on sleep, screen time, and physical activity while 30 percent met none of the recommendations.

The aforementioned 5 percent scored the best results on the test of cognitive abilities. But as the researchers noted, the more individual recommendations the child met, the better their cognition.

When examined on the basis of individual recommendations, less than two hours of recreational screen time in a day was linked to the most beneficial effect on cognition.

"I think that the overarching goal here is that parents should consider the whole 24-hour day of their children and put realistic rules or limits in place for how long they are on their screens for, having bedtime rules, and making sure to encourage physical activity," Walsh said.

In terms of limitations, the data was only recorded once and could not account for how behavior changes over time. The data was also self-reported, which meant there could be inaccuracies in how participants answered one or more of the questions.

And of course, the study was an observational one which meant a causal relationship could not be established. Future studies, the authors said, can try to establish this and also test how behaviors change over time.

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