Children who spend many hours a day glued to the TV or playing computer video games may be harming their ability to concentrate and focus on tasks in school, researchers suggest.
A study by psychologists at Iowa State University found that kids who exceeded the recommended two hours per day of screen time were 1 1/2 to two times more likely to have attention problems in the classroom.
Both the American Academy of Pediatrics (AAP) and the Canadian Paediatric Society recommend that parents limit a child's screen time to one or two hours daily.
"There isn't an exact number of hours when screen time contributes to attention problems, but the AAP recommendation of no more than two hours a day provides a good reference point," said lead author Edward Swing, a psychology doctoral candidate.
"Most children are way above that. In our sample, children's total average time with television and video games is 4.26 hours per day, which is actually low compared to the national average."
Co-author Douglas Gentile, an associate professor of psychology at Iowa State, said research has suggested that the average child in the U.S., and likely in Canada as well, spends many more hours per day with screen-based technology.
A study earlier this year by the Kaiser Family Foundation found kids aged eight to 18 devote almost eight hours on average per day to entertainment media, or about 53 hours per week.
"We were interested in seeing how children's media habits might be influencing various aspects of their lives," said Gentile, explaining that the study involved more than 1,300 children in grades 3, 4 and 5, and 210 college students.
The researchers, whose paper was published Monday in the journal Pediatrics, assessed the elementary school children using reports from parents and kids about their video game and television habits, as well as teacher reports of attention problems.
The college students provided self-reports of total screen time and attention problems.
"We had the teachers rate every child in the study on a number of things, including their school performance, their aggressive behaviour and their pro-social behaviour, as well as their attention problems," Gentile said from Ames, Iowa.
The results were quite startling, he admitted. "In just one year, we would see attention problems in the classroom getting worse related to how much time kids are in front of television and video games."
Gentile said the analysis did not look at whether the children had formal diagnoses of attention-deficit hyperactivity disorder, or ADHD, but their antsy behaviours "are the things that would get a child referred to the school psychologist to get tested for an attention problem."
Dr. Dimitri Christakis, director of the Center for Child Health, Behaviour and Development at Seattle Children's Hospital, said worries about the possible effects on children's attentiveness have been around for decades, beginning with the advent of TV programs aimed specifically at kids.
Scientific evidence has been inconclusive, he said, with various studies producing conflicting results.
"But there are certainly many well-done studies - and this is one of them - that have found a link between use of media and shortened attention spans," said Christakis, who was not involved in the research.
Video games, with their fast-paced action, flickering lights and high-decibel, shoot-'em-up sounds, are particularly overstimulating to the brain, he said from Seattle.
"It actually causes people to view this high level of stimulation as normative. And by comparison, life is sort of boring. It doesn't happen fast enough.
"Life isn't as interesting as video games are."
While overdoing screen time may be linked to poor attention, as the study suggests, Judith Wiener wonders if there are other factors in the home that contribute to both a child's inattention and the choice to spend hours watching TV, playing video games or texting friends.
Wiener, a professor of school and clinical child psychology at the Ontario Institute for Studies in Education, said it may be that a focus on media technology means children aren't getting enough exercise - which can lead to a lack of concentration.
As well, some kids may stay up late playing online video games, leading to poor attention caused by not enough sleep.
"I'm not saying these are the factors, what I'm saying is the study does not rule them out," she said. "I think the study would have been more solid had they looked at some of these other possible factors. More research is needed to look at that."
Gentile agreed, saying the authors aren't claiming that electronic media are the cause of diminished attention. "We're just trying to say that it looks like it may turn out that media are one of the causes."
Still, the research suggests parents can help their children by limiting daily screen time, he said.
"This demonstrates that parents probably aren't nearly as powerless as they might feel. Here might be a first thing that they can do that might help their children, so that the problem doesn't get worse and they don't need medication some day."