Those with sleep-disordered breathing tended to have a larger body-mass index and a higher waist circumference relative to their peers. More than 15 percent had primary snoring, the researchers found.

Until recently, enlarged tonsils or adenoids were believed to cause most sleep-disordered breathing in children, but the. In the study, researchers examined 700 children between the ages of 5 and 12 randomly chosen from 18 public elementary schools in Pennsylvania. About 25 percent of children had mild sleep-disordered breathing and 1.2 percent had moderate sleep-disordered breathing, defined as five or more breathing pauses per hour. Unlike in adults, a large neck circumference was not a predictor of sleep-disordered breathing in children, the study authors note in their report in the Zorana issue of SLEEP. -- Children with chubby bellies are more likely to have sleep-disordered breathing, a condition that's associated with behavioral problems, hyperactivity and difficulty staying awake at school, new research shows.

Each child had a physical exam and was monitored for nine hours at a sleep laboratory using polysomnography, which measures brain electrical activity, heart activity, airflow, respiration and oxygen saturation during sleep.