Kids who get even a little more sleep may behave better in school, a small new study suggests. The study included 34 kids, ages 7 to 11. They did not have sleep disorders. They got an average of 9 hours of sleep a night. They also had no problems with mental health or learning. Children were randomly divided into 2 groups. One group went to bed an hour earlier than usual for 5 days in a row. The other group stayed up an hour later than usual for 5 days. On average, the first group got about one-half hour of extra sleep daily. The second group got about an hour less. Before the study, teachers answered questions about each child's mood and behavior in class. After the study, they answered the same questions. Teachers ranked the kids in the sleep-deprived group as more restless, impulsive and moody than they were before the study. Kids who got more sleep were less likely to show these traits than they were before. Teachers were not told who was in each group. The journal Pediatrics published the study online. HealthDay News and CNN.com wrote about it October 15.

By Claire McCarthy, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Just one-half hour of extra sleep every night can make a real difference in your child's behavior.

That's the finding of a study published today. It appears in Pediatrics, the official journal of the American Academy of Pediatrics.

Researchers at McGill University in Canada studied 34 children, ages 7 to 11. They were healthy and had no mental health or learning problems. They also were getting enough sleep (8½ to 9½ hours) every night.

The children were randomly divided into two groups. The first group was asked to go to bed an hour earlier for five school nights in a row. For the second group, bedtime was an hour later. Sleep was measured using an actigraph, a contraption that looks something like a wristwatch. The device measures movement. It was used to help figure out if the kids were actually asleep or not.

The children in the sleep-extension group slept only about one-half hour more. (It's not always easy to fall asleep earlier!) Children in the sleep-restriction group got an hour less sleep each night.

Researchers asked parents to rate how sleepy their children seemed. They also asked teachers to rate them on how moody they were and how restless and/or impulsive their behavior was. The teachers didn't know which group the children were in.

The kids in the sleep-restriction group, not surprisingly, were sleepier. They were also moodier and more restless and impulsive. But here's what was a little surprising: There were also changes in the sleep-extension group. Though these kids were getting what we consider enough sleep before the study, with more sleep they were less sleepy, less moody and less restless and impulsive. Just one-half hour of extra sleep made a real difference in their behavior.

What Changes Can I Make Now?

The moody, restless and impulsive behaviors that the teachers were watching for can really affect a child's academic and social success in school. This study adds to the evidence that getting enough sleep is crucial to a child's well-being.

We don't really know what "enough" sleep is. We talk about 8 hours, and for adults that does seem to be the minimum for good physical and mental health. But for children, with growing and developing minds and bodies, the number may be higher. Some studies suggest that getting 10 hours of sleep a night lowers the risk of childhood obesity. So it may be that 10 is a better number for children. Certainly this study would suggest that more is better!

Here are some things you can do to help your child get enough sleep:

• Get the TV out of the bedroom.
• If your child has a cell phone, don't charge it in the bedroom at night.
• Have a regular bedtime that allows for 10 or so hours of sleep a night, and enforce that bedtime.
• Have a relaxing bedtime routine that starts an hour or so before the bedtime. Don't let your child play video games or watch TV until the last minute!
• Work with your child to come up with a schedule that allows homework to be finished at least an hour before bedtime.
• Don't overschedule your children. Make sure that they have enough time in their day not only to do homework but also to relax.
• Set a good example yourself. Turn off the television and do those relaxing evening routines. too!

What Can I Expect Looking to the Future?

More and more studies have been looking at the role of sleep in our health and well-being. It is increasingly clear that sleep has a crucial role. I hope that we will not only learn more about the role of sleep, but figure out how to apply what we learn every day -- and every night.