Researchers are reporting that violent content on the TV or computer during the day disrupts sleep for preschool children. And it’s worse for any TV or computer time in the evening regardless of content, according to Michelle Garrison, PhD, and colleagues at the Seattle Children’s Research Institute in Seattle.
The finding comes from week-long sleep diaries prepared by parents of 612 three-, four-, and five-year-olds at the start of a randomized trial, Garrison and colleagues reported in the journal Pediatrics.
Here are the details in a report from MedPage Today:
“The bottom line is that we see violent media use [in the daytime] and any screen time at all in the evening is associated with a negative impact on sleep in kids of this age,” Garrison told MedPage Today and ABC News.
It’s not news, she said, that using a computer or watching TV affects sleep in pre-schoolers, sometimes making it hard for them to fall asleep or wake up in the morning and even causing nightmares.
But Garrison said this study is the first to look at the impact of different types of content, rather than just screen time itself. It’s the first step in a randomized trial that aims to see what effect changing types of media content has on sleep in preschoolers.
The snapshot captured by the media diaries showed that the children were watching TV or using a computer about 73 minutes a day on average, although some were above four hours, Garrison and colleagues reported.
That’s less than some other studies, which have reported averages of two, three, or even four hours in the same age group, she said.
As well, only one child in 10 had a TV in the bedroom, while other studies have placed the proportion at between 20% and 45%, Garrison said.
“There’s a couple of ways in which our sample was doing … a little bit better in terms of healthy media use than what you’d normally see across the country,” she said.
In the sleep diaries, parents reported how often the child had trouble getting to sleep, woke up repeatedly, had nightmares, had difficulty waking in the morning, or was tired in the daytime.
The responses were used to calculate a “sleep problem score” ranging from five to 15: the maximum meant the child had all of the problems from five to seven nights a week, while the low score indicated that all of the problems were rare, occurring at most once a week.
Garrison said sleep patterns in pre-schoolers are changeable, but such sleep diaries have been shown to give “a pretty good picture of what’s going on.”
She and her colleagues found that 18% of parents reported at least one of the sleep problems occurring five to seven nights a week.
To get an idea of what content was causing problems, the researchers conducted regression analyses, calculating the effect of an additional hour of TV or computer time on the sleep score and broken down by type of content.
They found:

• Each additional hour of evening media use – regardless of content — was associated with a 0.743-point increase in the sleep problem score, which was significant at P<0.001.
• Each additional hour of daytime use with violent content was associated with 0.398-point increase in the score, significant at P<0.01.

For the most part, Garrison said, children were not watching super-gory adult fare or playing shoot-’em-up computer games. Instead they were seeing cartoons and other material aimed at slightly older children.
“The amount of violence wasn’t huge,” she added – an average of 19 minutes a day.
But parents should be aware that even content that seems innocuous could be a problem, she said.
“Bugs Bunny counts as violence in this study, and so does Batman and so does Pokémon,” she said, because there was no difference in the effect.
“When we stopped and looked at types of violence – slapstick funny violence in Bugs Bunny or superhero violence in Batman or more realistic violence – we didn’t see a difference in terms of the impact on sleep,” Garrison said.
But even small amounts of age-inappropriate TV may have an impact on preschool children because their “cognitive ability to distinguish between reality and fantasy is not developed,” according to Jeannine Gingras, MD, a pediatric sleep expert in Charlotte, N.C.
It also has to do with what the child perceives to be frightening, even if it’s not violent, she told MedPage Today/ABC News. Clowns, for instance, can give many children nightmares, or kids’ movies that seem benign to adults can be disturbing to children.
“I had one [5-year-old] child who had horrible sleep difficulties from [watching] ‘Monsters, Inc.’ which I thought was cute,” she said.
One clinical implication of the study, Garrison said, is that pediatricians can help – not by condemning all type of media use, but by suggesting parents restrict their kids to appropriate content during the day and forbidding use in the evening.
That approach, she said, is “actually pretty doable for most families.”
Such advice is a “critical part of my patient care, particularly when children present with behavioral, academic or weight-related problems, all of which have also been linked to sleep problems and screen time,” according to Nusheen Ameenuddin, MD, of the Mayo Clinic in Rochester, Minn.
She told MedPage Today/ABC News that Garrison’s study adds to a growing body of research suggesting that screen time and bedtime simply don’t mix.
Ameenuddin said she recommends that parents “go dark” to help their kids sleep — “remove TVs from children’s bedrooms, limit or eliminate media use before bedtime, and create a bedtime routine that is free of electronic stimulation to gently transition the child into sleep.”
Garrison and colleagues cautioned that the findings are based on cross-sectional data and it’s possible that unmeasured factors play a role. As well, the study uses parental reports, which are subject to possible over- or under-reporting of aspects of media use.