Narcolepsy and Excessive Daytime Sleepiness

A patient with unexplained sleepiness or fatigue presenting in a primary care setting often poses both a diagnostic and therapeutic dilemma. The etiology of the sleepiness may not be readily apparent. The patient and the general public may be at risk of serious personal injury unless prompt treatment is initiated. The risk of injury creates for the practitioner significant medical and legal responsibilities. Of all the different causes of excessive daytime sleepiness, narcolepsy should always be considered. Historically, the word “narcolepsy” was first coined by Gelineau in 1880 to designate a pathological condition characterized by irresistible episodes of sleep of short duration recurring at close intervals. In the same paper, he wrote that attacks were sometimes accompanied by falls or “astasias.” In the 1930s, Daniels emphasized the association of cataplexy, hypnagogic hallucinations, sleep paralysis, and excessive daytime sleepiness. Calling these symptoms the “tetrad” of narcolepsy Yoss, Daly, and Vogel described sleep-onset rapid eye movement sleep (REM) in narcoleptic patients. In 1963, Rechtschaffen et al. reported sleep-onset REM periods in narcolepsy. Narcolepsy is a neurological syndrome that is characterized by abnormal sleep, including excessive daytime sleepiness often with disturbed nocturnal sleep and pathological manifestations of REM. The REM abnormalities include early REM during sleep onset and cataplexy. Cataplexy is an abrupt and reversible decrease or loss of muscle tone, most frequently elicited by emotion.