Hypocretin Deficiency in Human Narcolepsy

Narcolepsy-cataplexy is a neurological disorder affecting 0.02–0.18% of the general population. The syndrome is characterized by excessive daytime sleepiness (EDS), fragmentation of nocturnal sleep, and intrusion of REM sleep events into wakefulness (e.g., cataplexy, sleep paralysis, and hypnagogic hallucinations). Daytime sleepiness and cataplexy are the most consistent symptoms of the syndrome. Sleepiness is the most disabling symptom. It is characterized by unpredictable and irresistible sleep attacks on a background of constant daytime sleepiness. Cataplexy, the sudden occurrence of muscle atonia triggered by emotions such as laughing or anger, is almost pathognomonic for the disorder. Nocturnal polysomnography is conducted to exclude other causes of daytime sleepiness, and multiple sleep latency tests (MSLTs) are carried out to demonstrate excessive daytime sleepiness and sleep onset REM periods, which are also characteristics of the disorder. Current therapeutic options are purely symptomatic. Modafinil is the most common treatment for sleepiness, and antidepressant compounds have some therapeutic effect on cataplexy and REM-related symptoms. Sodium oxybate (GHB) is a sedative hypnotic that improves disturbed nocturnal sleep and reduces cataplexy and sleepiness after long-term administration. These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.