Three other classic symptoms of narcolepsy, which may not occur in all patients, are:
- Cataplexy: Sudden episodes of loss of muscle function, ranging from slight weakness (such as limpness at the neck or knees, sagging facial muscles, or inability to speak clearly), to complete body collapse attacks may be triggered by sudden emotional reactions such as laughter, anger, or fear and may last from a few seconds to several minutes. The person remains conscious throughout the episode
- Sleep paralysis: temporary inability to talk or move when falling asleep or waking up. It may last from a few seconds to a few minutes
- Hypnagogic hallucinations: vivid, often frightening, dream-like experiences that occur while dozing or falling asleep.
- Daytime sleepiness, sleep paralysis, hypnagogic hallucinations: Can also occur in people who do not have narcolepsy
In most cases, the first symptom of narcolepsy is excessive and overwhelming daytime sleepiness. The other symptoms may begin alone or in combination months or years after the onset of the daytime sleep attacks.
There are wide variations in the development, severity, and order of appearance of cataplexy, sleep paralysis, and hypnagogic hallucinations in individuals. Only about 20 to 25 percent of people with narcolepsy experience all four symptoms. The excessive daytime sleepiness generally persists throughout life, but sleep paralysis and hypnagogic hallucinations may not.
The symptoms of narcolepsy, especially excessive daytime sleepiness and cataplexy, often become severe enough to cause serious disruptions in a person’s social, personal, and professional lives and severely limit activities.