More active kids have easier time falling asleep

NEW YORK (Reuters Health) - If you're one of those parents who likes to let their kids run themselves ragged so they fall asleep more easily, you may be onto something: the more activity kids get, the faster they'll drop off to sleep, according to a new study.

The study, in 591 seven-year-olds, also found that kids who spent more time in sedentary activities took longer to actually fall asleep after they went to bed.

Up to one in six parents of school-aged children report that their child has difficulty falling asleep, Dr. Ed A. Mitchell of the University of Auckland in New Zealand, the study's lead author, told Reuters Health by email. The study's findings, he said, emphasize that physical activity isn't only important for fitness, heart health, and weight control, but also for good sleep.

Mitchell and his team had children wear an activity-measuring device around their waists for 24 hours. They report their findings in the Archives of Disease in Childhood.

Most children took about 26 minutes to fall asleep after bedtime, they found. The more activity a child did, the less time it took him to fall asleep.

"We showed that one hour of vigorous activity (equivalent to running) reduced the time to fall asleep by almost 6 minutes," Mitchell said.

"However, the average amount of vigorous activity was only 43 minutes," Mitchell said. Also, he added, the children tended to be active in short bursts. "Their activity might better be described as stop-go rather than continuous as an adult might do when they exercise."

And for every hour a child spent each day being sedentary, it took them 3 minutes longer to get to sleep.

The researchers also found that children who took less time to get to sleep stayed asleep for longer, and vice versa.

"Fortunately, difficulty getting to sleep wasn't associated with other health problems," Mitchell said, although getting less sleep has been linked to obesity.

SOURCE: Archives of Disease in Childhood, September 2009.