narcolepsy

Rare neurological disorder characterized by an abnormal tendency to fall asleep. Often associated with cataplexy, it is controlled by drugs.

Narcolepsy was reported to affect around 1 in 2,000 people in the USA in 2000. Narcoleptics tend to have low levels of the neurotransmitter hypocretin. Hypocretin suppresses activity in the medial medulla, the part of the brain that makes the body limp during dream sleep, thus preventing accidents. As the medial medulla is not suppressed in narcolepsy, sufferers tend to become limp and drowsy during times of stress and excitement.