A growing body of research shows strong associations between TV in the bedroom and numerous health and educational problems. Children with bedroom TVs score lower on school tests and are more likely to have sleep problems. Having a television in the bedroom is strongly associated with being overweight and a higher risk for smoking.

One of the most obvious consequences is that the child will simply end up watching far more television — and many parents won't even know. "If it's in the bedroom, the parents don't even really know what the kids are watching," said Leonard H Epstein, professor of paediatrics and social and preventive medicine at the School of Medicine and Biomedical Science at the State University of New York at Buffalo. "Oftentimes, parents who have a TV in the kids' bedrooms have TVs in their bedrooms." Moreover, once the set is in the child's room, it is very likely to stay. "In our experience, it is often hard for parents to remove a television set from a child's bedroom," Epstein said.

New York Times