Dan Marsula, Post-Gazette Disrupted sleep, disrupted kids Click photo for larger image.

Snoring early in childhood is a strong indicator that youngsters will develop attention and hyperactivity problems that may only grow worse as they age, a new study shows.

"These findings strengthen the hypothesis that untreated sleep breathing problems in childhood can contribute to the development of hyperactivity," said Dr. Ronald Chervin, a sleep researcher at the University of Michigan and lead author of the findings published late last month in the journal Sleep.

Three years ago, Chervin and his colleagues reported that kids who snored regularly were twice as likely as non-snorers to have hyperactivity or attention problems at the same time. Among boys under age 8, the rate was four times greater.

That study included 866 children ages 2 to 13 who were surveyed in several pediatric clinics. The new report is based on a follow-up survey mailed to those same families four years later. Parents of 229 of the children, now ages 6 to 17, responded.

The children in the original study who snored regularly, vs. those who did not, were four times more likely to have developed new symptoms of hyperactivity four years later.

Similar behavior was noted among children who had other symptoms of obstructive sleep apnea, in which there is repeated pausing in breathing during the night that disrupt sleep and can affect blood oxygen levels.

The trend held true even after researchers took into account which youngsters had already been diagnosed as hyperactive in the first study, and which ones were taking prescription medicines for the behavior during the follow-up study.

The boys under 8 who had the worst sleep-breathing problems during the first study were nine times more likely to have developed new hyperactivity four years later than boys the same age who hadn't had sleep problems.

Chervin, director of the University of Michigan Health System's Aldrich Sleep Disorders Laboratory and an associate professor of neurology at the university's medical school, along with other sleep and breathing researchers, have built up a large body of evidence about how sleep disorders may affect children's brains.

They argue that breathing problems during sleep reduce the quality of sleep, curb oxygen levels and affect kids' behavior during the day.

Studies of small groups of children who have been treated for sleep-breathing problems -- usually with the removal of the tonsils and adenoids -- suggest that behavior may improve as sleep improves.

But while there is a strong association between the two problems, the researchers caution that definitive proof remains elusive, and may never be obtained because it would be unethical to take a group of children with sleep-breathing problems and only treat half of them so their behavior could be compared years later.

Still, Chervin said the new study is the first to show that sleep problems come before hyperactive behavior, and that one predicts the other, by following a group over a long time and assessing them at two different points.

The researchers concede that they have focused on children with a mild to moderate level of hyperactivity, and that it's not clear if the findings would apply to children with severe cases.

They also note that more precise evaluations of breathing problems and sleep might illustrate the link better.

But until more studies are done, Chervin suggests that parents pay closer attention to their children's sleep and their own.

"Getting enough sleep, adopting good sleep habits and seeking medical attention for issues such as habitual snoring, daytime sleepiness and breathing interruptions like sleep apnea can have a huge impact on the life of a child or an adult," he said.