Daytime sleepiness, sleep paralysis, and hypnagogic hallucinations also occur in people who do not have narcolepsy, more frequently in people who are suffering from extreme lack of sleep.  Cataplexy is generally considered to be unique to narcolepsy.

In most cases, the first symptom of narcolepsy to appear is excessive and overwhelming daytime sleepiness.  The other symptoms may begin alone or in combination months or years after the onset of the daytime naps.
 

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.
 

Although these are the common symptoms of narcolepsy, many (although less than 40% of people with narcolepsy)also suffer from insomnia for extended periods of time.  This can be from (A) an excess of sleep or (B) common use of self-medications such as energy drinks.
 

The symptoms of narcolepsy, especially the excessive daytime sleepiness and cataplexy, often become severe enough to cause serious problems in a person's social, personal, and professional lives and severely limit activities.

Narcolepsy is a neurological condition most characterized by Excessive Daytime Sleepiness (EDS), episodes of sleep and disorder of REM or rapid eye movement sleep.  It is a type of dyssomnia.

The main characteristic of narcolepsy is overwhelming excessive daytime sleepiness (EDS), even after adequate nighttime sleep.  A person with narcolepsy is likely to become drowsy or to fall asleep, often at inappropriate times and places.  Daytime naps may occur with or without warning and may be irresistible.  These naps can occur several times a day. They are typically refreshing, but only for a few hours. Drowsiness may persist for prolonged periods of time.  In addition, night-time sleep may be fragmented with frequent wakenings.

Four 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.  Episodes may be triggered by sudden emotional reactions such as laughter, anger, surprise, 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 waking up. It may last a few seconds to minutes. Often frightening but not dangerous.

•  Hypnagogic hallucinations:  Vivid, often frightening, dream-like experiences that occur while dozing, falling asleep and/or while awakening.

•  Automatic behavior:  Automatic behavior occurs when a person continues to function (talking, putting things away, etc.) during sleep episodes, but awakens with no memory of performing such activities. It is estimated that up to 40 percent of people with narcolepsy experience automatic behavior during sleep episodes.