Narcolepsy is among the leading causes of excessive daytime sleepiness (EDS) and is the most common neurologic cause. Despite a prevalence similar to that of multiple sclerosis and a socioeconomic impact that may be as high as that of epilepsy, and despite the availability of effective treatments, knowledge about narcolepsy often remains limited even among neurologists.

Its classic form—narcolepsy with cataplexy—is a distinct neurologic disease with characteristic clinical and paraclinical findings. The definition of the variants of narcolepsy, however, remains a matter of controversy. The International Classification of Sleep Disorders has defined narcolepsy as “a disorder of unknown etiology, which is characterized by excessive sleepiness that typically is associated with cataplexy and other REM sleep phenomena such as sleep paralysis and hypnagogic hallucinations.”<sup>10American Sleep Disorders Association ICSD—International Classification of Sleep Disorders: Diagnostic and Coding Manual  Diagnostic Classification Steering Committe, Thorpy MJ (Chairman) Rochester, MN: American Sleep Disorders Association (1990). 

Cliccare qui per andare alla sezione Riferimenti</sup> In the absence of cataplexy, this definition may be misleading because the association of EDS with other rapid eye movement (REM) phenomena can occur in diseases other than narcolepsy. A better understanding of the cause and clinical spectrum of this syndrome awaits further research.