Preschool-aged children were more likely to have sleep problems if they watched violent TV shows and videos but a program to help families use more educational alternatives helped, a new study suggests.

Observational studies have long shown an association between media use and children's sleep problems. Now researchers in the U.S. say they have evidence of a cause-and-effect relationship.

The children's program Sesame Street was one of the educational shows recommended in an experiment on how violent programming hinders preschoolers' sleep. (Beth A. Keiser/Associated Press)

"This study demonstrates that a healthy media use intervention can improve child sleep outcomes and adds evidence that the relationship between media and sleep in preschool-aged children is indeed causal in nature," Michelle Garrison and Dr. Dimitri Christakis of Seattle Children's Research Institute conclude in Monday's issue of the journal Pediatrics.

In the experiment, 565 families in the Seattle area with children aged three to five were randomly assigned to two groups:

• Visits, phone calls and mailings from a case manager who tried to help them replace violent media and age-inappropriate media content with educational-type videos.
• A control group that received nutrition-related mailings instead.

Participating parents were told the study targeted media and aggression rather than sleep to prevent bias.

Researchers assessed sleep in terms of how long it took for them to fall asleep, night wakings, nightmares, difficulty waking and daytime tiredness.

Children who received the treatment had lower odds of sleep problems, an effect that lasted for a year but started to fade six months after the program ended, Garrison and Christakis reported.

The fact that the intervention focused on content choices rather than viewing time suggests the content itself played a key role, they said.

The pair suggested that clinicians and parents consider healthy media choices in preventing and treating sleep problems in children.

"Given that early childhood sleep problems have been associated with a range of deleterious outcomes, both acute and long-term, including increased injuries, behavioural and emotional problems, difficulties in school, and obesity, the availability of useful, feasible strategies is critical," the authors said.

In the study, parents were encouraged to watch programs with their children, because co-viewing can increase parent awareness of the media content and some evidence suggests it enhances the positive effect of programming that is educational and benefits children.

Recommended programs included Dora the Explorer, Curious George and Sesame Street.