4 Characteristics of Narcolepsy

Narcolepsy is a disorder most commonly characterized by excessive daytime sleepiness. But, it also has other symptoms and four defining features that make it unique among all sleep disorders. Even though only 1 in 3 people with narcolepsy have all of the symptoms and features, knowing about them can still be useful in identifying those who may be at risk.


Excessive Daytime Sleepiness

Excessive daytime sleepiness is one of the defining features of narcolepsy

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This is an increased desire to fall asleep and a lack of energy during the day even after an adequate night's sleep. In narcolepsy, sleep begins to intrude upon wakefulness and elements of wakefulness intrude upon sleep. Therefore, narcoleptics are prone to falling asleep at all times, with little warning (so-called "sleep attacks").

Overnight sleep may be disturbed as well. People with narcolepsy are more likely to go into rapid eye movement (REM) sleep within the first hour after falling asleep (and often within the first 15 minutes). Sleep is also more fragmented with frequent transitions between sleep stages.

Daytime sleepiness may result in double or blurred vision and automatic behaviors such as "zoning out" while driving. The Epworth sleepiness scale identifies the degree of excessive sleepiness. Scores higher than 15 out of 24 are often reported by narcoleptics.

Sleepiness in narcolepsy typically improves after a brief nap. And narcoleptics typically wake up feeling refreshed in the morning.


Hypnagogic Hallucinations

These involve vivid, often frightening hallucinations that occur in the transitions between sleep and wakefulness, with onset most likely as a person is falling asleep or waking up.

Hypnagogic hallucinations result when REM sleep and associated dreaming, mixes with wakefulness. These hallucinations are often visual, but other experiences may occur as well.


Sleep Paralysis

Sleep paralysis is a common experience that may occur normally in people, but it can also be found in narcolepsy. It consists of the inability to move for one or two minutes upon awakening.

In addition, there may be accompanying feelings of suffocation or even a looming presence within the room. The episodes tend to be quite frightening. Though they may occur ordinarily, especially during sleep disruptions, they also are a sign of narcolepsy.



Cataplexy is the sudden and transient loss of muscle tone that is triggered by an emotional event. For example, laughter, joking, or excitement may cause a temporary weakness. This weakness may only involve a part of the body, such as the face, neck, or knees, and recovery may be quick.

It typically lasts only a few minutes and consciousness remains intact. Severe episodes may cause falls.

Interestingly, cataplexy occurs in almost no other disorder. So, if it is present, narcolepsy with cataplexy (or type 1 narcolepsy) is the likely diagnosis. Its presence again relates to an intrusion of REM sleep into wakefulness, for paralysis normally occurs when we are asleep so that we do not act out our dreams.

By Brandon Peters, MD
Brandon Peters, MD, is a board-certified neurologist and sleep medicine specialist.