Parents may went to limit their children's computer use and TV viewing time to ensure their psychological well-being.
Children who spent two hours or more a day watching TV or playing on a computer were more likely to have psychology difficulties.
The negative impact of screen time was not remedied by increasing a child's physical activity levels.
Hiding the TV remote and games console controller is a good thing to do to kids if it's the only way to limit the time they spend in front of a screen, according to a study published Monday.
The study, conducted by researchers from the University of Bristol, found that youngsters who spend hours each day in front of the TV or games console have more psychological difficulties like problems relating to peers, emotional issues, hyperactivity or conduct challenges, than those who don't.
And contrary to what earlier studies have indicated, the negative impact of screen time was not remedied by increasing a child's physical activity levels, says the study, published in the journal Pediatrics.
The researchers got 1,013 children between the ages of 10 and 11 to self-report average daily hours spent watching television or playing -- not doing homework -- on a computer. Responses ranged from zero to around five hours per day.
The children also completed a 25-point questionnaire to assess their psychological state, and the time they spent in moderate to vigorous activity was measured using a device called an accelerometer, which was worn around the waist for seven days.
The researchers found that children who spent two hours or more a day watching television or playing on a computer were more likely to get high scores on the questionnaire, indicating they had more psychological difficulties than kids who did not spend a lot of time in front of a screen.
Even children who were physically active but spent more than two hours a day in front of a screen were at increased risk of psychological difficulties, indicating that screen time might be the chief culprit.
Earlier studies have found that while more time spent in front of a screen led to lower well-being, physical activity improved one's state of mind. That led researchers to believe that upping physical activity levels could counteract the negative impact of watching TV or playing on the computer.
And many parents and children think that spending a lot of time on the computer or in front of the television is OK if it's part of a "balanced lifestyle," the study in Pediatrics says.
"Excessive use of electronic media is not a concern if children are physically active," the study says.
But its findings indicate that might not be the case, and the researchers advise parents to limit their children's computer use and TV viewing time to ensure their "optimal well-being."
Read more about the benefits of limiting screen time from the American Academy of Pediatrics.