It's an oft-heard lament that children spend far too much time watching TV, DVDs or playing video games – and a study suggests that an alarming number of babies are being turned into ``screen time" junkies as well.

In a study of more than 1,000 families, U.S. researchers found that 40 per cent of 3-month-olds and about 90 per cent of kids aged 2 years or younger regularly watch television, DVDs or videos.

The study found that the infants and toddlers were spending up to 1 1/2 hours a day viewing television shows or DVDs, an activity the researchers say can be harmful to cognitive development.

Study co-author Dr. Dimitri Christakis, a pediatrician at Children's Hospital in Seattle, said certain TV programs and infant-aimed videos such as Baby Einstein and Brainy Baby are marketed as being advantageous for the developing child.

"What we know is that the claims that are made by the purveyors of these products, both explicitly and implicitly, that they can make your children smarter or more musical or more mathematical, are entirely unsubstantiated," he said Monday from Seattle.

"There's absolutely no scientific evidence in support of those claims, nor is there any scientific basis theoretically to believe them," said Christakis, co-author of the book The Elephant in the Living Room: Make Television Work For Your Kids.

"And the best available evidence to date suggests that certainly watching a lot of TV before the age of two is in fact harmful – harmful in terms of children's attentional abilities later in life, harmful in terms of their cognitive development, both of those measured at school entry."

Even the TV program Sesame Street, which has been shown as beneficial for number and letter recognition among 3- to 5-year-olds, is associated with language delays when viewed by children under three, he said.

"Sesame Street wasn't designed for kids that young, but it's watched by kids that young because parents think if it's good for a 3-year-old, it's good for a 2-year-old. And parents want to believe their 1-year-old is as advanced as the average 3-year-old."

To conduct the study, published in Tuesday's issue of the Archives of Pediatrics and Adolescent Medicine, the researchers conducted a telephone survey of 1,009 parents of children age two to 24 months. They analyzed four television and DVD content categories: children's educational, children's non-educational, baby DVDs/videos and adult television (such as talk shows or sports programming).

On average, children began watching TV at nine months old, with an average viewing time of 40 minutes a day. Those who began getting screen time at three months of age watched less than an hour per day, and by age 24 months they were watching more than 1.5 hours per day.

Parents watched with their children more than half the time. ``The results here show that only 32 per cent of parents report watching television or videos with their child every time the child watches," the authors write.

Christakis said parents have several reasons for allowing television and DVD/video viewing: 29 per cent believe that television is educational or good for their child's brain; 23 per cent see it as enjoyable or relaxing for their child; and 21 per cent think it gives them time to get things done while the child is entertained.

"People have the assumption that parents used this as a babysitter, that's their primary motivator," he said. "But in fact what we found was that the Number 1 reason they give is that it's good for their children's brain."

"They think it's actually good and it's not surprising that they think that because they've been marketed to quite aggressively with claims to that effect. But the reality is quite different."

The Canadian Pediatric Society recommends that preschoolers watch an hour or less of TV a day and that school-age kids keep their screen time to two hours maximum. The American Academy of Pediatrics discourages any screen time for children under 2.

Dr. Anthony Ford-Jones, a pediatrician in Burlington, Ont., said the problem with infants and toddlers watching TV or DVDs is that it's a passive activity.

"It's very attractive, but it's probably not as good for the child's brain as actively doing something and finding their own fun," Ford-Jones said Monday. "A child's mind at the earliest stages works in such an active way. They can be fascinated by things . . . They'd be better off with a cupboard full of pots and pans than they would be with passive sitting in front of something that looks cute and pretty and colourful and has jingles and nice tunes."

"And you can extrapolate that to older kids as well, who have lost their ability to make their own amusement because they're so used to being fed stuff through the TV," he said, noting that the lack of physical activity is a huge contributor to an epidemic of childhood obesity in North America.

Christakis said most parents he deals with feel guilty about their television use, but instead of feeling guilty they should just try using it more wisely.

"It's very difficult to be a parent, and most parents find themselves relying on TV in one way or another. The real challenge for them is to find a way t