(CNN) — Watching violence on television or TV before bedtime can lead to sleep problems for preschoolers, according to a new study in the journal Pediatrics.Experts have known for some time that too much TV time can negatively impact our sleep, but this new research finds that what young children watch and when they watch it can make a difference as well.The study looked at the television viewing habits and sleep problems of more than 600 preschoolers in Seattle.When children watched age appropriate TV in the morning or afternoon, they didn’t have problems with their sleep, but when the shows contained violence, young people were more likely to experience nightmares and wake up feeling tired.Part of the problem, researchers say, is that younger children are watching shows meant for older kids, and preschoolers can’t yet distinguish fantasy from reality.”For a 7- to 10-year-old, they are really at a point where cognitively they can grasp that that’s not real violence and they can see the humor in it — it’s not frightening for them. But 3- to 5-year-olds just aren’t developmentally there yet,” explains study author Michelle Garrison, Ph.D., with the Seattle Children’s Research Institute.Garrison also found that watching television right before bedtime made it more difficult for children to get to sleep, meant more nightmares and waking up during the night, even if the shows were educational and geared specifically for young children.”Screen time during the hour before bed can get kids more aroused and then they’re going to have a harder time falling asleep,” explains Garrison.She suggests parents turn the TV off at least 60 minutes before kids get tucked in.Shows that are meant for adults carry risks as well, she says, and she advises parents not to watch potentially violent programs such as the evening news when children are in the room.”Even if they think the child isn’t paying attention, the child is absorbing it and they’ll see shootings and war footage and they really don’t have the capacity to understand that that’s not necessarily happening right there is their neighborhood right now,” says Garrison.Children who had televisions in their rooms tended to watch more than other children and saw more violent programming. When parents were asked about having a set in the bedroom, many said they thought it would help their child sleep, but this is not what the research shows.”Sometimes parents will look at their child zoned out in front of the TV and think they are really relaxed. But often when kids get that glazed over, zoned out look they are actually over stimulated and not relaxed,” explains Garrison.The American Academy of Pediatrics recommends that preschoolers watch no more than two hours of television a day. High quality programming geared for this age group offers not only educational benefits, the Academy points out, but can help with building social skills as well.”It can help children learn about cooperative problem solving, about how to negotiate things, help them learn empathy,” says Garrison.Experts offer these tips to help parents with their children’s viewing habits. First of all, take the television out of the bedroom and watch TV with your child whenever you can.”And watch what you watch; in other words, is that something that you think is appropriate for your child. You may want to watch the program first to see if it’s ok for your child to watch or if it’s too intense. And finally, don’t be afraid to turn the TV off,” says Pediatrician Don Shifrin, former Chair of the American Academy of Pediatrics’ Committee on CommunicationsAnother good source for families is Common Sense Media, according to Garrison. This website offers reviews on TV programs and movies, looking at the levels of violence, scary content and educational value.

Copyright CNN 2011