• Narcolepsy, a sleep-wake disorder of unknown cause, has been reported as occurring in the pediatric population, but only two reports of cases in the literature have included polysomnographic data on children with narcolepsy. We compared the clinical and polysomnographic data on a series of eight patients 15 years of age or younger and an adult comparison group with narcolepsy. All patients presented with excessive daytime sleepiness, and no significant difference was found between groups for the incidence of cataplexy, hypnagogic hallucinations, and sleep paralysis. On polysomnographic evaluation the pediatric group had increased total sleep time, percent-stage 3/4 sleep, percent rapid eye movement sleep, and decreased stage 1 sleep, which all are expected age-related differences. The pediatric group also showed a greater degree of daytime sleepiness and an increased frequency of sleep-onset rapid eye movement periods. While pediatric patients with narcolepsy resemble adults in their mode of presentation and the incidence of accessory symptoms, the increase in severity of sleepiness highlights the importance of diagnosing narcolepsy in children as early as possible so that treatment can be initiated.