More than two hours a day spent watching television or playing computer games could put a child at greater risk for psychological problems, suggests a new study.
British researchers found the effect held regardless of how active kids were during the rest of the day.
"We know that physical activity is good for both physical and mental health in children and there is some evidence that screen viewing is associated with negative behaviors," lead researcher Dr. Angie Page of the University of Bristol told Reuters Health in an e-mail. "But it wasn't clear whether having high physical activity levels would 'compensate' for high levels of screen viewing in children."
Page and her colleagues studied more than 1,000 kids between the ages of 10 and 11. Over seven days, the children filled out a questionnaire reporting how much time they spent daily in front of a television or computer and answering questions describing their mental state -- including emotional, behavioral, and peer-related problems. Meanwhile, an accelerometer measured their physical activity.
The odds of significant psychological difficulties were about 60 percent higher for children spending longer than two hours a day in front of either screen compared with kids exposed to less screen time, the researchers report in the journal Pediatrics. For children with more than two hours of both types of screen time during the day, the odds more than doubled.
The effect was seen regardless of sex, age, stage of puberty, or level of educational or economic deprivation.
Psychological problems further increased if kids fell short of an hour of moderate to rigorous daily exercise in addition to the increased screen time. However, physical activity did not appear to compensate for the psychological consequences of screen time.
Give kids screen-time budget
The researchers also found that sedentary time itself was not related to mental wellbeing. "It seems more like what you are doing in that sedentary time that is important," said Page, noting the lack of negative effect found for activities such as reading and doing homework.
Page and her team acknowledge several limitations in their study, including the potential for a kid to inaccurately recall his or her activities when filling out the questionnaire.
Dr. Thomas N. Robinson of the Stanford University School of Medicine, who was not involved in the study, said the new research was not enough to decipher whether the relationship between screen time and psychological wellbeing was truly cause-and-effect.
"They would have needed to do an experiment, a randomized controlled trial, to see whether limiting television or computer time improves psychological difficulties when compared to a control group that does not limit screen time," he told Reuters Health in an e-mail.
Robinson noted that his own related research, conducted in this way, found that limiting screen time reduced weight gain, aggression and consumer behaviors in kids.
"There are already lots of reasons to reduce kids' screen time and this is potentially another," said Robinson. "In our studies we find that giving children a screen-time budget and helping them stick to that budget is the most effective way to reduce their television, video game, computer and other screen time, and to improve their health as a result."
He usually aims for a budget of about an hour per day, or a reduction of at least 50 percent from a kid's starting screen time.
"Parents as well as kids tell us that budgeting kids' screen time has profound positive effects on their families' lives," added Robinson.