Not many parents are likely to challenge the following wisdom from comedian - and father - Chris Rock: "Kids always act up the most before they go to sleep."

As if that fact isn't aggravating enough, a recent study by University College London published in the journal Pediatrics has shown that children with fluctuating bedtimes are more likely to exhibit behavioral problems than those who bed down at the same time night after night.

The study identifies some of the problems caused by ever-shifting sleep schedules as hyperactivity, scrapping with peers and emotional difficulties.

According to Dr. David Ramey, a board-certified neurologist and sleep physician at Kootenai Health's Sleep Disorders Service, "I think at the most basic level, the important thing for children is consistency.

"And that means consistency in bedtimes throughout the week, including weekends. This is especially true for younger kids," Ramey added.

"We've found that sleep difficulties do not usually start overnight. They develop slowly, and if not dealt with, can become a real problem over time."

In addition to being the land of Nod, sleep is also the land of misconception. Many mistakenly believe sleep involves the temporary shutting down of the brain and that a restful night is, essentially, a no-brainer.

Not true, says a Harvard University paper. "Prior to the era of modern sleep research in the early 1920s, scientists regarded sleep as an inactive brain state. In 1929, an invention that enabled scientists to record brain activity challenged this way of thinking. From recordings known as electroencephalograms (EEGs), researchers could see that sleep was a dynamic behavior, one in which the brain was highly active at times, and not turned off at all."

So what is the purpose of sleep?

"Sleep is universal," Ramey said. "All living things sleep to some degree or other, but we don't know exactly what - other than being a restorative process - sleep does."

We all do, however, know the purpose of insufficient sleep, which is to make us miserable. The situation, however, is more dire than that. There are other health problems that can crop up when we don't put in enough rack time.

"Insufficient sleep is associated with a number of chronic diseases and conditions such as diabetes, cardiovascular disease, obesity, and depression," said the Centers for Disease Control and Prevention. "Not getting enough sleep is associated with the onset of these diseases and also may complicate their management and outcome."

The UCL study of 10,000 children folds into this equation the problem of irregular bedtimes, stressing that interruptions of natural body rhythms can be responsible for sleep deprivation. "This in turn," the study said, "has been found to undermine the way the brain matures and children's ability to behave well."

According to Dr. Duane Craddock, a board-certified pediatrician with Coeur d'Alene Pediatrics, consistent sleep schedules begin with consistent sleep hygiene. "We're preaching this more and more in the electronic age," he said.

"I recommend that the only thing you do in your bed is sleep. It's not the time to talk on the phone. And kids need to be off their computers and away from TV and video games. Basically you're winding down and telling your body that it's time to sleep.

"When your child sleeps in on, say, a weekend, he's altered his sleep patterns for the next two to four days. A late-night Saturday can take a child into Wednesday of the next week to get their sleep straight again."

Ramey agrees, emphasizing the importance of a pre-bedtime rituals such as baths and storytime.

"I think a consistent bedtime routine should limit things that will activate the child - especially anything with excessive light exposure."

At the end of the day, the experts say, it's become a cultural thing. Our 21st century lifestyle has made sleep, in many cases, an expensive luxury.

"I think there's more of that with teens and adults than with young children," Craddock said. We've become a busy society and that busyness doesn't allow for slowing down. A lot of sleep dysfunction comes from a lifestyle of electronics and a lack of outdoor physical activity."

Online:

http://healthysleep.med.harvard.edu/

http://www.cdc.gov/features/sleep/