What is Narcolepsy?
Narcolepsy is a sleep disorder that causes overwhelming and severe daytime sleepiness. Pathologic sleepiness is characterized by the fact that it occurs at inappropriate times and places. The daytime sleep attacks may occur with or without warning, and can occur repeatedly in a single day. Persons with narcolepsy often have fragmented nighttime sleep with frequent brief awakenings.
The following are some little known facts about narcolepsy:
- Frequently, narcolepsy is unrecognized for many years. There could be a delay of 10 years between the onset of the condition and the diagnosis.
- Approximately half of adults with narcolepsy retrospectively report symptoms beginning in their teenage years. For most patients, narcolepsy begins between the ages of 15 and 30 years. It less frequently occurs in children younger than age 10 years of age.
- Narcolepsy may lead to impairment of social and academic performance in otherwise intellectually normal children.
- Narcolepsy is a treatable condition. A multi-modal approach is most effective (medications, a regular nighttime sleep schedule, and scheduled naps during the day)is required for the most favorable outcome.
Narcolepsy Symptoms and Signs
Narcolepsy is typically characterized by the following four symptoms with varying frequencies:
- Excessive daytime sleepiness
- Cataplexy (sudden and temporary loss of muscle tone often triggered by emotions such as laughter)
- Hallucinations (vivid dreamlike experiences that occur while falling asleep or upon awakening)
- Sleep paralysis (paralysis that occurs most often upon falling asleep or waking up; the person is unable to move for a few minutes)
Less frequently persons have all four symptoms.
Narcolepsy is believed to result from a genetic predisposition and abnormal neurotransmitter (hypocretin, also known as orexin) functioning and sensitivity.
Understanding of narcolepsy stems primarily from research involving narcoleptic dogs (for example, special laboratory-bred Dobermans and Labradors). In these animal models, the disorder is transmitted in an autosomal recessive fashion and is characterized mainly by cataplexy.
A small percentage of human cases are inherited and, unlike the canine form, are transmitted in an autosomal dominant manner.
The neurotransmitter hypocretin was identified in the last few years and is strongly associated with narcolepsy in dogs with a genetic predisposition. Hypocretin levels in human subjects with narcolepsy have been found to be undetectable or
low in several recent studies of patients with narcolepsy. Hypocretin appears to modulate activity in the hypothalamus (the part of the brain associated with sleep). The deficiency of hypocretin might produce sleep attacks. The drug modafinil (Provigil) is useful in the treatment of narcolepsy is believed to activate hypocretin-containing nerve cells.
Last Reviewed 11/20/2017
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