Children who watch TV or use a computer for more than two hours a day are more likely to have poor mental health than those who do not, according to a study.
Scientists added that a child doing physical exercise did not compensate for any excess time spent in front of a screen.
Around 1,000 children took part in the study at the University of Bristol, the results of which were published in Pediatrics.
A sensible guideline is limiting a child’s viewing time to two hours a day, the scientists said.
The amount of time the children spent in front of a screen was recorded and their psychological well being was measured through a questionnaire.
An activity monitor also clocked both the time they spent being idle and the time they spent being active over a seven-day period.
Five areas were covered by the questionnaire: emotional difficulties, conduct problems, hyperactivity or inattention, friendships and peer groups, and problems relating to friends and peer groups.
It was found that those who watched TV or used a computer for longer than two hours each day were more likely to have psychological difficulties. This risk increased if they did not do enough exercise, the study noted.
Other studies have also shown similar negative effects on young people who both spend a lot of time in front of a screen and do little physical activity.
The study’s lead author, Angie Page, said: “Not all screen viewing is bad and at low levels physical activity may well compensate. But the two-hour limit is a good, sensible guideline for parents.”