People who suffer from narcolepsy are prone to falling asleep abruptly at any time. They could be talking to someone, driving a car or doing housework. Brief episodes of cataplexy, which is a loss of muscle tone in part of the body, can also occur in response to intense emotions such as surprise, laughter or anger, and can cause the person to fall.
In some cases, upon awakening or just before sleep, narcoleptics experience a brief paralysis that may be accompanied by hallucinations, making this disorder especially frightening. As if that were not enough, the quality of their sleep is also poor.
This rare disease, which affects about 0.05% of the population, varies considerably in intensity. It can cause multiple sleep attacks per day, lasting from a few minutes to nearly an hour, or only a few episodes per year.
The causes are not well known. Hypocretin (also known as “orexin”), a neurotransmitter responsible for waking up, has been found to be lacking in the brains of people with this disorder. Some studies suggest that an autoimmune reaction completely destroys the nerve cells that produce hypocretin.