Narcolepsy is characterized mainly by uncontrollable daytime sleepiness. Sudden onset of sleep may occur at inappropriate times such as while working or driving, having a conversation, or being in any sedentary or non-stimulating situation.
The signs and symptoms of narcolepsy include:
- Excessive daytime sleepiness
- Sudden loss of muscle tone. This condition, called cataplexy, can cause a range of physical changes, from slurred speech to complete weakness of most muscles, and may last for a few seconds to a few minutes. Cataplexy is uncontrollable and is often triggered by intense emotions, usually positive ones such as laughter or excitement, but sometimes fear, surprise or anger. For example, your head may droop uncontrollably or your knees may suddenly buckle when you laugh. Some people with narcolepsy experience only one or two episodes of cataplexy a year, while others have numerous episodes each day. About 70 percent of people with narcolepsy experience cataplexy.
- Sleep paralysis. People with narcolepsy often experience a temporary inability to move or speak while falling asleep or upon waking. These episodes are usually brief — lasting one or two minutes — but they can be frightening. You may be aware of the condition and have no difficulty recalling it afterward, even if you had no control over what was happening to you.
- Hallucinations. These hallucinations, called hypnagogic hallucinations, may take place when a person with narcolepsy falls quickly into REM sleep, as he or she does at sleep onset at night and periodically during the day, or upon waking. Because you may be semi-awake when you begin dreaming, you experience your dreams as reality, and they may be particularly vivid and frightening.
Other characteristics
Other signs and symptoms of narcolepsy include restless nighttime sleep and occasional automatic behavior. During episodes of automatic behavior, you continue to function during sleep episodes — even talking and putting things away, for example — but you awaken with no memory of performing such activities, and you generally do not perform these tasks well. As many as 40 percent of people with narcolepsy experience automatic behavior. People with narcolepsy may also act out their dreams at night by flailing their arms or kicking and screaming.
The signs and symptoms of narcolepsy can begin anytime up to your 50s, but they most commonly begin between the ages of 10 and 25. Narcolepsy is chronic, which means signs and symptoms may vary in severity, but they never go away entirely.