[Narcolepsy].

Narcolepsy is a neurologic sleep disorder characterized by excessive daytime sleepiness and by intrusions into wakefulness of physiological aspects of rapid eye movement (REM) sleep such as cataplexy, sleep paralysis and hypnagogic hallucinations. Although epidemiologic studies show that it is nearly as widespread as Parkinson's disease or multiple sclerosis, narcolepsy is often not much known and confused with other neurologic disorders and psychiatric pathologies. The hard psychosocial impact on patient's life can be mitigated by an early diagnosis and by a targeted pharmacological treatment alleviating the most debilitating symptoms. Through a deep assessment of international literature we traced an updated picture of narcoleptic disorder in order to provide a useful tool of neurobiological, clinical, and therapeutic knowledge. Particular attention has been turned to the new discoveries on the possible role of the neuropeptide orexin in the genesis of narcolepsy, which open new pharmacological and research frontiers in this field.