Excessive Daytime Sleepiness More Common in Obese Children With Habitual Snoring

"The epidemic of childhood obesity has prompted remarkable changes in the relative proportions of symptomatic overweight or obese children being referred for evaluation of habitual snoring," write David Gozal, MD, and Leila Kheirandish-Gozal, MD, from Kosair Children's Hospital Research Institute and University of Louisville in Kentucky. "However, it remains unclear whether obesity modifies the relative frequency of daytime symptoms such as excessive daytime sleepiness."

The study sample consisted of 50 consecutive, nonobese, habitually snoring, otherwise healthy children and 50 obese children matched for age, sex, and ethnicity. Age range was 6 to 9 years, and body mass index z score in the obese children was greater than 1.67. All participants had an overnight polysomnographic evaluation, followed by a multiple sleep latency test on the following day.

Both groups had similar mean obstructive apnea/hypopnea index values, with episodes per hour of total sleep time 12.0 ± 1.7 in nonobese children vs 10.9 ± 1.5 in obese children. Compared with nonobese children, however, obese children had significantly shorter mean sleep latency (12.9 ± 0.9 minutes vs 17.9 ± 0.7 minutes). Mean sleep latencies were 12.0 minutes or less in 21 obese children but in only 5 nonobese children.

For the whole cohort, there were significant associations among mean sleep latency, obstructive apnea/hypopnea index, proportion of total sleep time with oxygen saturation of less than 95%, and respiratory arousal index. However, the slopes and intersects of the linear correlation of mean sleep latency with any of these variables were consistently greater in the group of obese children.

"The likelihood of excessive daytime sleepiness for obese children is greater than that for nonobese children at any given level of obstructive sleep apnea [OSA] severity and is strikingly reminiscent of excessive daytime sleepiness patterns in adults with obstructive sleep apnea," the study authors write.

"In the presence of OSA of similar severity, obese children are at increased risk for EDS," the study authors conclude. "Furthermore, obese, habitually snoring children present magnified reductions in MSL [multiple sleep latency] (ie, increased sleep propensity) at any level of OSA severity. Therefore, the clinical presentation of habitual snoring and sleep-disordered breathing in obese children differs from that of children who are not obese, such that symptoms of EDS and difficulty remaining awake for an obese child should prompt evaluation for OSA."

Pediatrics. 2009;123:13-18.