Sleep Disorders: Narcolepsy

Narcolepsy is a neurological disorder that affects the control of sleep and wakefulness. People with narcolepsy experience excessive daytime sleepiness and intermittent, uncontrollable episodes of falling asleep during the day. These sudden sleep attacks may occur during any type of activity at any time of day.

Narcolepsy usually begins between the ages of 15 and 25, but it can become apparent at any age. In many cases, narcolepsy is undiagnosed and, therefore, untreated.

What Causes Narcolepsy?

The cause of narcolepsy is not known; however, some experts think narcolepsy may be caused by a deficiency in the production of a chemical called hypocretin by the brain. In addition, researchers have discovered abnormalities in various parts of the brain involved in regulating sleep which seem to contribute to symptom development.

According to experts, it is likely narcolepsy involves multiple factors that interact to cause neurological dysfunction and sleep disturbances.

What Are the Symptoms of Narcolepsy?

Symptoms of narcolepsy include:

• Excessive daytime sleepiness (EDS): In general, EDS interferes with normal activities on a daily basis, whether or not a person with narcolepsy has sufficient sleep at night. People with EDS report mental cloudiness, a lack of energy and concentration, memory lapses, a depressed mood, and/or extreme exhaustion.
• Cataplexy: This symptom consists of a sudden loss of muscle tone that leads to feelings of weakness and a loss of voluntary muscle control. It can cause symptoms ranging from slurred speech to total body collapse depending on the muscles involved and is often triggered by intense emotion, for example surprise, laughter or anger.
• Hallucinations: Usually, these delusional experiences are vivid and frequently they are frightening. The content is primarily visual, but any of the other senses can be involved.
• Sleep paralysis: This symptom involves the temporary inability to move or speak while falling asleep or waking up. These episodes are generally brief lasting a few seconds to several minutes. After episodes end, people rapidly recover their full capacity to move and speak.

Reviewed by The Sleep Medicine Center at The Cleveland Clinic..