The research used data from the ten-year Adolescent Brain Cognitive Development study, which began in September 2016.
The children in the study displayed better cognition when they met more of the recommended guidelines, though the children that met either just the screen time guideline or both the screen time and the sleep guidelines showed stronger cognitive development.
Walsh along with his research team observed the data of 4,520 children spread across 20 locations in the US. While about half met the sleep recommendation, only 37 percent met the guideline for limited screen time and 18 percent met that for physical activity. The children had also provided spit samples, took questionnaires and got their cognitive functions measured by playing with puzzles.
At the end of the study the researchers found that children, who spent less than two hours of their free time on screens, slept for nine to 11 hours per night and had at least one hour of physical activity per night, performed better as compared to those who didn't fall into any of those specifics.
Cutting back on screen time, along with the right amount of sleep and physical activity, is linked to improvements in coginition among children, a study suggests. The study controlled for household income, parental and child education, ethnicity, pubertal development, body mass index and whether the child had had a traumatic brain injury.
He continued and said that "Based on our findings, pediatricians, parents, educators, and policymakers should promote limiting recreation screen time and prioritizing healthy sleep routines during childhood and adolescence".
The children in the study averaged 3.6 hours of recreational screen time each day. "It is tempting to take solace in findings that cognitively challenging screen activities can benefit cognition, but, if given a choice, most children already consistently and predictably choose more stimulating screen activities over less stimulating ones". Almost 30 percent of the children didn't meet any of the recommended guidelines, just over 40 percent met one, and 25 percent met two. They were asked how much they sleep, how much they exercise and how much time they spend in front of screens.
According to the study's authors, additional research is needed to better understand the effects of different kinds of screen time on cognition, and they point out that given the study's observational nature, it does not prove a causative link between screen time on cognition.
Surprisingly, meeting only the physical activity recommendation was not associated with higher scores on the cognitive tests.
"Irrespective of our findings", the authors stress, "physical activity remains the most important behaviour for physical health outcomes, and there is no indication in the literature that it negatively affects cognition".
But some studies have suggested that the potential for damage is more about the type of content on these screens and whether parents are involved than about the amount of time using them.
"Each minute spent on screens necessarily displaces a minute from sleep".