Résumé
The destruction of orexin/hypocretin neurons results in the sleep disorder narcolepsy type 1 (NT1). Formerly known as narcolepsy with cataplexy, the major clinical features of NT1 are excessive daytime sleepiness (EDS), cataplexy, and other rapid eye movement (REM) sleep phenomena (e.g., sleep paralysis and sleep-related hallucinations). Orexin neurons are located exclusively in the lateral hypothalamus, but project widely through the brain, and especially in hypothalamic and brainstem structures that play a central role in autonomic and cardiovascular regulation. This chapter focuses on the pathophysiological mechanisms underlying dysautonomia in narcolepsy, related to orexin deficiency, and the clinical aspects of autonomic impairment in narcolepsy. A general overview of dysautonomia in other central hypersomnolence disorders (narcolepsy type 2, idiopathic hypersomnia, and Kleine-Levin syndrome) is provided, with clinical implications discussed.