The more time children spend watching TV or playing video games at night, the less they sleep, according to a new study in the journal Pediatrics. The researchers said reducing screen time may make it easier to get children and teens to go to bed earlier.

For the study, researchers in New Zealand tracked what children were doing in the 90 minutes before bedtime to see how those activities impacted the time they fell asleep. In surveying more than 2,000 children and adolescents, ages 5 to 18, they found that watching TV or playing video games trumped such activities as reading, getting ready for bed or doing homework, listening to music and other activities when it came to pushing back sleep.

Watching TV or other "screen time" was the dominant activity for all of the children, making up about a half-hour of the 90-minute period. And those with later sleep onset reported up to 13 minutes more screen time just before heading to bed, compared to those who slept earlier.

Cutting back on screen time in the short period before children head off to bed could help kids get to sleep earlier, said study leader Louise Foley, who led the research at the University of Auckland.

Besides looking at how much screen time kids had, the team of researchers examined how long it took the child subjects to fall asleep. The two went together.

The findings didn't surprise Dr. Dimitri Christakis, a distinguished professor of pediatrics at the University of Washington in Seattle, who told HealthDay, "There is growing evidence that media use around sleep time is bad for sleep initiation."

He said the study suggests "it's not so much having a bedtime for your children. You have to have a bedtime for their devices."

According to the HealthDay article, "Although previous research has found that television viewing and other 'screen-time' activities are linked with a decline in the length of time children and teens sleep, the new study is believed to be the first to look at the pre-bedtime period by asking youth (or their parents, for the younger children) to account for their time in detail."

The study said that sleep duration has been shrinking for the last century. Noted, "Not getting enough sleep has been linked to such issues as inadequate sleep is associated with behavior and health issues in this younger population. Although they cautioned that causality could not be inferred from their cross-sectional study, they added that teens' and children's pre-sleep time in front of a video screen 'may be implicated through disrupting or displacing sleep.'"

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