Is lack of sleep a problem in your home?

Sleep quality is another issue causing measurable effects in kids' behaviour. A survey of five- to seven-year-old American children showed a high correlation between children who snored or had other sleep disturbances and those who showed mild signs of ADHD. In another study, half of children with sleep apnea a condition that causes people to temporarily stop breathing and interrupts their sleep had their adenoids removed to solve the problem. This group saw their grade point average increase from 2.4 to 2.8, while the grades of the other half, who kept their adenoids, didn't change.

Perhaps not surprisingly, poor sleep also exacts its toll on mood. "Mood is pretty uniformly affected in most of the studies that have looked at children who are sleep restricted," says Owens. She says that includes irritability, whininess, low frustration tolerance and a less-positive outlook.

If poor school performance, decreased cognitive function, irritability and hyperactivity are some of the effects of insufficient sleep, what are some of the causes?

One of the big causes of poor sleep is childhood obesity, says Ian MacLusky, director of the sleep clinic at The Hospital for Sick Children in Toronto. "The problem having an increasing impact is childhood obesity," says MacLusky. "Thirty per cent of American kids are now regarded as clinically obese. That's causing sleep apnea, hyperventilation and sleep disturbances. And the reason is inactivity. It's not that people are eating more; they're just doing less."

Lack of activity, whether in an obese child or not, also causes poor sleep. "In the old days, kids walked to school," says MacLusky. "Now they insist on being bused or driven. They didn't have TV. They were outside playing with their mates in the street, kicking a ball around." Having a full, active day is one way to ensure a solid night's sleep, he says.

Another culprit of insufficient sleep is electronic diversions. Lots of parents say kids have too much homework, but MacLusky points to the number of hours the average North American child spends watching TV: "It's easy to blame schoolwork, but the boob tube is probably the biggest culprit." Owens agrees, reporting that many kids in her recent survey talked of TVs in their rooms. "The Cartoon Network is on 24 hours a day, and these kids are watching all kinds of things," she says. In teens, she says, Internet amusements are exacting their toll.

Owens also cites a shift in extracurricular activities into the evening hours to accommodate parents' work schedules: "Many kids who are nine to 11 years old have team practices from 7 to 9 p.m. They're vigorously exercising, which everybody tells you that you shouldn't do within three hours of bedtime. Of course they're wired, and by the time they get to bed, it's 10:30 or 11 p.m."

The 24-hour-a-day society is affecting us all, says MacLusky: "It's too easy to stay up and do things, and we're all pressured to do more and more." He says that the fix is easy but hard because it requires an attitude and lifestyle shift.

"It's doable," says Owens. "Parents have to become convinced that it's an issue that they have to pay attention to. You wouldn't give your child a diet of french fries if she wanted it." Parents must enforce limits around sleep: coaches have to be told that practice from 8 to 10 p.m. is out of the question, she says. "We have the opportunity to teach kids from an early age that sleep is important and that it's an important health behaviour," says Owens.

If rethinking priorities to shift the importance of sleep seems like the impossible dream, consider the reward. "The kids getting proper sleep have an edge, both physically and mentally," says Coren.In Part 2 of our three-part series on kids and sleep, meet families who are getting their school-age kids to bed on time (but not without a fight).