Being overweight or obese boosts a teenager's risk of developing the nighttime breathing disorder obstructive sleep apnea, new study findings hint.

Obstructive sleep apnea, or OSA, occurs when airway passages become blocked during sleep, cutting off breathing for brief but frequent periods. It is often accompanied by heavy snoring.

OSA is increasingly being recognized in children and the sleep disturbances caused by OSA can lead to daytime learning and behavior problems in children, as well as more serious health problems, such as high blood pressure.

In the new study, researchers found that the risk of OSA among a group of white adolescents aged 12 and older increased 3.5-fold with each upward increase in body weight classification.

The risk of OSA did not increase significantly with increasing body weight among younger children aged 2 to 11 years old. This was a little surprising to us initially, as obesity is generally considered to increase the risk of sleep apnea amongst all children, principal investigator Dr. Mark J. Kohler, research fellow at the Children's Research Center at the University of Adelaide in Australia, noted in a prepared statement.

Previous results have been inconsistent, however, and appear to be confounded by using mixed ethnic populations and different ages of children, he added.

In the study, a total of 234 children aged 2 to 18 years underwent overnight sleep studies after their parents reported that each snored at least one night a week. None of the kids had medical conditions that might cause them to snore or stop breathing during sleep.

The risk of OSA alone was not found to be greater among adolescents compared with younger children. When considering only children who had OSA (that is, at least one bout of interrupted breathing per hour of sleep), there was a clear increase in the proportion of kids who were overweight and obese with increasing age.

However, after allowing for social and economic status, body weight, and differences in sleep study evaluations, there was no link between being overweight or obese and OSA in children younger than 12 years, even though about 30 to 40 percent of this group was overweight or obese.

By contrast, nearly all of the overweight (13 percent) and obese (nearly 53 percent) 12- to 18-year-old children had OSA; being heavy or obese was clearly associated with the condition in this age group, the researchers say.

In a report in the Journal of Clinical Sleep Medicine, the researchers emphasize that they evaluated only white children. Studies amongst different ethnic groups are necessary before these results can be generalized across races and applied clinically, Kohler commented in an email to Reuters Health.

SOURCE: Journal of Clinical Sleep Medicine, December 15, 2009

Medicine