'Parents should be aware that snoring is not a good thing.' It has been linked to poor school performance and other problems. The latest research is strongly suggestive of a cause-and-effect relationship between snoring and hyperactivity.

"The association is pretty strong, and we are saying it may be causal," said Dr. Ronald D. Chervin, director of the university's Sleep Disorders Center. "The sleep disruption itself may lead to hyperactivity."

Chervin and his colleagues from both the University of Michigan and the University of Washington evaluated 229 children, who were aged 6 to 17 at the time of the study. They were drawn from a group of 866 2- to 13-year-olds whose parents were surveyed originally in the late 1990s in the waiting rooms of pediatric clinics. The parents of 229 children returned the follow-up survey four years later.

Of the 229, 30 children were rated as hyperactive. And that hyperactivity was predicted by the habitual or loud snoring, sleepiness or sleep-disordered breathing in the original survey done four years before, the researchers found.

Snoring and other sleep problems, Chervin and his colleagues concluded, "are strong risk factors for future emergence or exacerbation of hyperactive behavior."

Oxygen Levels

The new study, Chervin said, is the first long-term look at the association. Children in the original study who snored regularly were about four times as likely to have developed new hyperactivity by the time the survey was done four years later. Snoring early in their lives predicted the children's new or worsened behavior problems four years later.

Exactly how the snoring may lead to the hyperactivity is not clear.

"One of the reasons could be the oxygen levels during the night are lowered repeatedly, every time the throat closes," Chervin said. At least in animal studies, he said, lowered oxygen brings about behavior changes.

Or, the sleep disruption may lead directly to the hyperactivity, Chervin added.

Adults who are sleep-deprived just look very sleepy, he said. "Kids may stay awake at any cost, including creating an environment that helps them stay awake at any cost," he added.

On the survey, parents were asked how often and how severely their child snored, and if the child had a tendency to struggle to breathe or stop breathing temporarily during the night, or had a hard time waking up. They were also asked about their child's behavior during the day, and whether there were attention problems.

'Snoring Is Not a Good Thing'

Another expert, Dr. Ann Halbower, medical director of the Pediatric Sleep Disorders Program at Johns Hopkins University Children's Center, said the new research makes the long-suspected link between snoring and hyperactivity "sound much more causal."

"It still isn't proof," she said. But the new research at least is strongly suggestive of a cause-and-effect between snoring and hyperactivity, she said.

However, as Halbower pointed out, there could be yet another explanation, such as an underlying problem that leads to both the snoring and the hyperactivity.

Until more is known, Chervin said, he urges parents to take their children's sleep problems seriously and to describe them to the child's pediatrician.

The most common treatment to stop the snoring is removal of the tonsils and the nearby adenoids, he said.

Halbower agreed that parents should be alert to chiildren's sleeping problems. "Parents should be aware that snoring is not a good thing," she said. It has been linked to poor school performance and other problems.

Good Night's Sleep Triggers Brain Changes

Another sleep study, reported in the June 30 issue of Neuroscience, found that getting a good night's sleep triggers brain changes that help improve memory.

Researchers at Beth Israel Deaconess Medical Center, in Boston, evaluated 12 healthy college students who performed a sequence of skilled finger movements similar to playing a piano, doing the exercise after a 12-hour period of wake or sleep while researchers performed MRI scans.

The cerebellum, one of the brain's motor centers controlling speed and accuracy, was more active after sleep, and the limbic system, which controls for stress and other emotions, was less active.

The students performed better after the sleep period.

More information: To help children learn more about sleep, visit the National Sleep Foundation.

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