Too much time spent in front of the screen, too little sleep and exercises related to cognitive development worse in children: study

According to a new study of more than 4,500 children aged eight to eight, the average American child spends 3.6 hours each day watching a computer, television, tablet or smartphone. 11 published yesterday in The Lancet Child & Adolescent Health.

The study was conducted by Canadian researchers but examined children in the United States using the Canadian 24-Hour Movement Guidelines for Children and Youth. These guidelines recommend that children spend nine to eleven hours of uninterrupted sleep, less than two hours of screen time and at least one hour of physical activity each day. Children who scored the best on language, memory, executive function, attention, and processing speed tests met these sleep, screen, and activity goals .

In the United States, 19 out of 20 children have failed to meet the quality of life criteria. While about half responded to the sleep recommendation, only 37% met the guideline for a limited screen time and 18% met this requirement for physical activity.

In their conclusions, the researchers took into account various other factors known to contribute to cognition, including household income and educational attainment.

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Improvements in cognition were associated with each additional recommendation, with time spent in front of a screen and sleep having the strongest correlation with improvement. The physical activity guide alone shows no association. This was surprising, according to the authors, and this might suggest that the measure of physical activity might not have been sufficiently accurate.

Although these statistics themselves are alarming, their ramifications can be even more worrying.

"The data suggest that good sleep and good physical activity are associated with improved academic performance, while physical activity is also related to improved reaction time, attention , memory and inhibition, "said Dr. Jeremy Walsh University of British Columbia, said in the press release of the study. The relationship between screen time and cognitive development has always been less clear, and this type of research is in its infancy.

Dr. Eduardo Esteban Bustamante, Assistant Professor of Kinesiology and Nutrition at the University of Illinois at Chicago, did not participate directly in the research. activity and recovery of sleep.

"Every minute spent on screens necessarily shifts a minute of sleep or cognitively stimulating activities," wrote Dr. Bustamante in a commentary that accompanied the study. "In the case of the use of the evening screen, this displacement can also be aggravated by an alteration of the quality of sleep."

In his commentary, Dr. Bustamante compares the problem of screen time with that of the childhood obesity epidemic and says that both have been propagated by their profitability for the industry, the convenience for parents and the pleasure of children. He warns that, in this sense, the findings of the new study "are a potential canary in a coal mine. If we want to better protect the minds of children than their bodies, we will have to be better scientists and citizens than we have been. "

According to the authors of the study, additional research is needed to better understand the effects of different types of screen time on cognition, and they point out that, given the observational nature of the study, nonetheless, the results suggest that "pediatricians, parents, educators and policy makers should promote the limitation of time spent in front of screens and prioritize healthy sleep routines throughout childhood and adolescence Said Dr. Walsh.

Nicky Mehtani is a physician in internal medicine at Johns Hopkins Hospital and is part of the ABC News Medical Unit.