MONDAY, Oct. 15 (HealthDay News) -- When children can get just a little more sleep each night, their school behavior and alertness levels improve, new research suggests.

"Even small changes in daily life that can allow children to add about a half hour of sleep could have a significant impact," said study author Reut Gruber, director of the attention behavior and sleep lab at the Douglas Institute at McGill University, in Quebec.

The finding is published online Oct. 15 and in the November print issue of Pediatrics.

For the research, Gruber randomly assigned 34 children, aged 7 to 11, to one of two groups. One group had their sleep restricted, with bedtimes moved back so they lost an hour of sleep, for five nights straight.

The other group had their bedtimes moved up, so they gained an hour of sleep time for five consecutive nights.

In all, 33 children finished the study.

The children wore wrist-watch like devices, called actigraphs, to record their sleep.

Gruber found the sleep-extension group slept on average just 27 additional minutes a night. Those in the restricted group slept, on average, 54 minutes less a night.

At the study start, both groups slept, on average, about nine hours. Children in this age group should sleep 10 or 11 hours, according to the National Sleep Foundation.

Teachers rated the children on standard measures of behavior, such as impulsivity, restlessness and emotional ability. They also noted daytime sleepiness.

Those in the extra sleep group did better, showing improvement in alertness, behavior and emotions, the researchers found. Those in the restricted group had declining scores on alertness.

The findings are no surprise, said Dean Beebe, a professor of pediatrics at the Cincinnati Children's Hospital Medical Center and the University of Cincinnati College of Medicine.

He has studied inadequate sleep and its effects on teen behavior. He cautioned parents, however, that the extra sleep can't be just for one night but should be a long-term change if their children are not sleeping enough.

"It's a lifestyle thing, not a quick one-night [change]," he said.

He pointed out that even though the children in the study, on average, were getting a fair amount of sleep -- nine hours or so -- they still did better when they got more sleep.

Study author Gruber said that children may be sleep-deprived for a number of reasons. They can get involved in electronic media past bedtime, including playing video games, watching television, texting or talking to friends.

Parents may also encourage too much activity at night, she said. When children are too busy with schoolwork and extracurricular activities, it often delays bedtimes, she said.

Advice? Prioritize sleep, Gruber said. Set and keep a consistent bedtime.

Don't allow electronics in the bedroom. Be sure the bedroom environment is comfortable, she said.

Beebe had some advice as well.

He told parents to remember that they still have control over household activity. Beebe promotes a pre-bedtime wind-down, starting a half-hour to an hour before the set bedtime. "Take the tempo down," he said. Instruct the kids to use the time to shower or bathe, read a book or otherwise relax.

More information

To learn more about children and sleep, visit the National Sleep Foundation.