Excessive daytime sleepiness in psychiatric disorders: Prevalence, correlates and clinical significance.

This study examined the prevalence of excessive daytime sleepiness, as measured by the Epworth Sleepiness Scale (ESS), in a cohort of adult psychiatric patients. A total of 300 psychiatric outpatients and an additional 300 healthy controls completed the ESS. Excessive sleepiness was defined by a score of > or =10.