Narcolepsy and the ability to resist sleep.

We describe five patients who presented with irresistible daytime sleepiness and who have the clinical and laboratory features of narcolepsy but differ from most patients with narcolepsy in their ability to resist falling asleep during the daytime. All of the patients described partial or complete remission of their symptoms. Using an HLA marker, the expected haplotypes for narcolepsy were found, but no specific genetic features were found associated with chromosome 6p that differentiated this group from patients with typical narcolepsy. Problems are discussed in the laboratory assessment of such patients using both the multiple sleep latency test and the maintenance of wakefulness test.