Too little sleep and excess screen time are clearly linked to a drop off in cognitive skills, such as language ability, memory and task completion, according to a study published Thursday.

Axar.az reports citing Sabah Daily.

On average, children aged eight to 11 spent 3.6 hours per day glued to a TV, mobile phone, tablet or computer screen, nearly double the suggested limit of two hours, researchers reported in The Lancet Child & Adolescent Health.

"We found that more than two hours of recreational screen time in children was associated with poorer cognitive development," said lead author Jeremy Walsh, a researcher at the Children's Hospital of Eastern Ontario Research Institute.

For sleep and exercise, the recommendations align with those of the World Health Organization, but Canada is the first country to propose limits for time spent in front of a back-lit screen.

Nearly 30 percent of children failed to meet any of the recommendations, more than 40 percent met only one, a quarter met two, and only 5 percent conformed to all three.

Half the children were getting enough sleep, 37 percent remained within the screen-time limits, and only 18 percent met the physical activity recommendation.

"The more individual recommendations the child met, the better their cognition," the study concluded, noting that screen time was the most important factor.

"Each minute spent on screens necessarily displaces a minute from sleep."