Neuroimaging in narcolepsy.

Narcolepsy is a chronic neurological disorder, has no specific cause, and is characterized by excessive daytime sleepiness and uncontrollable sleep attacks. In case of strong emotions such as laughter, anger or joy, a cataplexy (sudden loss of muscle tone, lasting for a short period of time) may occur (1, 2). Other symptoms of narcolepsy include sleep paralysis and hypnagogic hallucinations (3, 4). Narcolepsy can occur in both men and women at any age. The prevalence of narcolepsy shows similar values in North America and Western Europe, varying from 0.02% to 0.05% (5, 6). HLA DQB1-0602 ratio 85% and HLA DQA-102 95% ratios of people with narcolepsy were found (7, 8). In spite of the fact that 99% of the cases develops sporadically, the risk is 30 to 40 times higher in the first-degree relatives than in the normal population (6).