The frequency of sleep-disordered breathing (SDB) among children with inattention and hyperactivity was determined in 866 patients, aged 2.0 to 13.9 years (mean; 6.8 yrs), evaluated in two general pediatric clinics at the University of Michigan and University of Pittsburg. A Pediatric Sleep Questionnaire, for snoring, sleepiness, and risk of SDB, and two behavioral measures (an inattention/hyperactivity scale (IHS) from DSM-IV, and the hyperactivity index (HI) of the Conners’ Parent Rating Scale) were completed on each patient. Habitual snoring was associated with a high IHS score (>1.25), and showed a significant association with a high HI score (>60), reflective of hyperactive behavior; 22% of habitual snorers had HI>60, whereas only 12% of nonhabitual snorers had HI>60. Snoring, daytime sleepiness, and SDB scores showed significant associations with IHS and HI. The link between snoring and behavior was strongest for young boys <8 years old. In contrast, sleepiness and SDB showed similar associations in all age- and sex-defined groups. 
COMMENT. Inattention and hyperactive behavior, cardinal symptoms of ADHD, may be associated with increased daytime sleepiness, snoring and other symptoms of sleep-disordered breathing. Daytime sleepiness is linked to hyperactive behavior in boys and girls of all ages, whereas the association of snoring and behavior is limited to boys under 8 years of age. Questions regarding sleep habits and snoring are important in the evaluation of children with symptoms of ADHD. A possible causal relationship needs further study.
The causes of sleep problems in children with ADHD include stimulant medications, anxiety disorder, and environmental behavioral sleep deprivation . Objective measurements of sleep habits, such as polysomnography and actigraphy, have shown conflicting results, while parental ratings reveal an increased prevalence of sleep problems in children with ADHD. The child’s own perspective of sleep habits correlate with those of the parents (see Ped Neur Briefs June 2000; 14:47). If upper airway obstruction is excluded as a cause of snoring and sleep-disordered breathing, the substitution of clonidine for stimulant medication should be considered in ADHD children.