However, only one in 20 U.S. children aged between 8-11 years meet the three recommendations advised by the Canadian 24-hour Movement Guidelines to ensure good cognitive development - 9-11 hours of sleep, less than two hours of recreational screen time, and at least an hour of physical activity every day.
But now, experts warn that American children really are spending too much time in front of their TV, computer, and phone screens. "This study is showing that less than two hours of recreational screen time is beneficial for children".
Just 5% of children in the study met all three guidelines, and 30% met none of them.
Further studies are already focusing on the impact of screen time on the young people, and more results will be soon published.
Almost 30 percent of children failed to meet any of the recommendations, more than 40 percent met only one, a quarter met two, and only five percent conformed to all three. A surprising detail is the fact that children which only met the physical activity requirements do not show a better cognition level, although sport is usually thought as an activity which strengthens cognitive functions.
The researchers measured the children against widely recognised guidelines.
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The questionnaire found that children that met all three recommendations or met the sleep and screen-time recommendations - or just met the screen-time recommendations - performed noticeably better than children who met none of them, or met other combinations of the guidelines.
A Canadian research team looked at data from 4,500 United States children ages 8 to 11 and compared the kids' self-reported screen use to their performance on a test that measures markers of brain development. If you want your kids to do well in life, limit their screen time to less than two hours, encourage them to do physical activities and to have sufficient sleep, suggests new research.
Writing in a linked Comment, Dr Eduardo Esteban Bustamante, University of Illinois, USA, says: "Through a stress-adaptation lens, the strong associations between global cognition and meeting the recreational screen time recommendation found by Walsh and colleagues potentially reflect the interruption of the stress-recovery cycle necessary for growth in children who do not meet the recommendation".
"Based on our findings, paediatricians, parents, educators, and policymakers should promote limiting recreational screen time and prioritising healthy sleep routines throughout childhood and adolescence", Walsh added. The report said an average tween spends four and a half hours looking at screens for entertainment each day. She, however, was not part of the study. The researchers said that they were surprised with this finding, but they suggested that the measure used may not have been specific enough.
Screen time wasn't the only possible reason for children's worse thinking skills.