Young children who snore may be more than four times more likely to become hyperactive later in life than those who don't, according to a new study.

Researchers say the findings provide strong evidence that snoring and other symptoms of obstructive sleep apnea are major risk factors for hyperactivity in children. Obstructive sleep apnea, also known as sleep disordered breathing, is a common sleep disorder caused by a blockage in the airway that disrupts normal breathing during sleep.

"To our knowledge, this new study is the first long-term, prospective research to show that regular snoring and other clues to the possible presence of sleep apnea predict future development of inattention and hyperactivity," says researcher Ronald Chervin, MD, director of the University of Michigan Health System Sleep Disorders Laboratory, in a news release. "These findings strengthen the hypothesis that untreated sleep-breathing problems in childhood can contribute to the development of hyperactivity."

The results appear in the July 1 issue of the journal Sleep.

Read WebMd's Snoring Puts Kids' Health at Risk

Snore Now, Hyperactive Later?

In the study, parents of 229 children aged 2 to 13 completed questionnaires about their child's sleeping habits, snoring, sleep-disordered breathing, and hyperactivity at the beginning of the study and again four years later.

The study was conducted as a follow-up to an earlier study that showed children who snored regularly were twice as likely as those who didn't to have hyperactivity or attention issues. Thirty of the children were rated as hyperactive at the end of the follow-up period.

The results of this current study showed that children who snored or had other symptoms of sleep apnea, such as daytime sleepiness, at the start of the study were more likely to have developed hyperactivity four years later.

Researchers say the findings remained significant even after they took into account children who were already considered hyperactive at the start of the study.

They say the severity of sleep apnea symptoms was also associated with a greater risk of hyperactivity later in life. For example, the group of boys under age 8 who had the worst sleep-disordered breathing problems at the start of the study was about nine times more likely to have hyperactivity than boys the same age without sleeping problems.

They say that the results do not prove that sleep-disordered breathing causes hyperactive behavior but they do provide evidence to support this hypothesis.

They add that if sleep-disordered breathing does contribute to hyperactive behavior then the results highlight the importance of early recognition and treatment in children.

Read WebMd's Understanding Snoring -- the Basics

By Jennifer Warner, reviewed by Brunilda Nazario, MD

SOURCES: Chervin, R. Sleep, July 1, 2005; vol 28: pp 746-751. News release, University of Michigan.