Obese children are more likely to suffer from sleep-disordered breathing, a condition that's associated with behavioral problems, a new study has found. The conclusion was based on a study of 700 children between the ages of 5 and 12, researchers at Pennsylvania State University College of Medicine said in their report published in the June issue of SLEEP. In the study, the researchers randomly chose the children from 18 public elementary schools in Pennsylvania. 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. 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. More than 15 percent had primary snoring, the researchers found. Those with sleep-disordered breathing tended to have a larger body-mass index and a higher waist circumference relative to their peers. Unlike in adults, a large neck circumference was not a predictor of sleep-disordered breathing in children, according to the study. Until recently, enlarged tonsils or adenoids were believed to cause most sleep-disordered breathing in children, but the study found no link between tonsil size and disordered breathing. Instead, obesity may be playing the greater role, said study author Edward O. Bixler. "Risk factors for sleep-disordered breathing in children are complex and include metabolic, inflammatory and anatomic factors," Bixler said. "Because sleep-disordered breathing in children is not just the outcome of anatomical abnormalities, treatment strategies should consider alternative options, such as weight loss and correction of nasal problems."