[Narcolepsy. An illness in transition].

The signs of narcolepsy have been known since the last century and the tetrad of symptoms was described 50 years ago: excessive sleepiness, cataplexy, sleep paralysis, and hallucinations. Polysomnography typically shows decreased sleep and REM sleep latency, and laboratory testing reveals a high association with the human leucocyte antigens (HLA) DQB1*0602 and DQA1*102. Actual studies suggest disturbances in the orexin (hypocretin) neurotransmitter system. However, the exact pathophysiology is still unclear. In Germany, about 1500 patients diagnosed with narcolepsy are known. The prevalence in Caucasian populations is estimated at 50/100,000. Thus, the number of undiagnosed patients is likely to be high.