Children who spend more than two hours a day on smartphones seven times more likely to develop ADHD

Young children who spend more than two hours a day starting at smartphones and other screens are seven times more likely to develop attention disorders, research suggests.

The study of 3,500 children found that high levels of screen time were associated with a far greater risk of attention deficit hyperactivity disorder (ADHD) by the age of five.

Parents were asked to report the total amount of time that three-year old children spent looking at television screens and gaming and mobile devices.

They then completed a behaviour checklist and their behaviour in school at age five.

The average three year old was found to be spending 90 minutes a day looking at screens, the study by the University of Alberta found.

The one in seven who watched more than two hours had a 7.7-fold increased risk of meeting criteria for ADHD, the study published in the journal PLOS ONE found.

The study found that children who spent more time doing organised sports were less likely to exhibit behavioural problems.

Study leader Professor Piush Mandhane, a paediatrician, said: "We found screen time had a significant impact at five years of age.”

Recently England’s chief medical officer urged parents not to allow children to spend more than two hours at a time looking at screens.

Dame Sally Davies also said smartphones should be banned from meal times and left outside of bedrooms at night.

Prof Mandhane said the new findings suggested screen time should be far more limited for pre-school children. He said: "Our data suggests between zero and 30 minutes a day is the optimal amount of screen time.

"The preschool period is an ideal time for education on healthy relationships with screens, and we believe our data shows that you can't start too early."

The research identified factors that provided protection from the negative effects of screen time.

Good quality sleep had a small impact, while participation in organised sports was found to have a highly significant protective effect.

Prof Mandhane said: "Interestingly, it wasn't physical activity on its own that was protective; the activity needed to have structure.

"And the more time children spent doing organised sports, the less likely they were to exhibit behavioural problems."

Fellow author Sukhpreet Tamana said: "A lot of the things you do through organised activities are really important for young kids early on. It sets the stage for development amongst children.

"I think in lieu of screen time, it would be beneficial for parents to increase opportunities for other structured activities instead."