Recognizing the Symptoms of Narcolepsy

Narcolepsy symptoms may be lurking beneath the surface

Cataplexy
  What is it:

A sudden, generally brief (<2 min) loss of muscle tone, with retained consciousness, triggered by strong emotions.1,2

Cataplexy is the most specific symptom of narcolepsy.1,2,11,15 The duration of cataplexy attacks is usually short, from a few seconds to generally less than 2 minutes.1 The frequency of cataplexy is variable, ranging from less than one attack per month to more than 20 attacks per day.1 The presentation of cataplexy differs widely among patients, ranging from very subtle partial attacks triggered by laughter to frequent complete attacks involving collapse to the ground, triggered by a variety of emotions.1,2,15

  Diagnostic challenge:

The patient may be unaware of subtle forms of cataplexy. Ask the patient to bring someone who knows him or her well to the clinical interview.1,3

Cataplexy differs widely among patients and its subtle manifestations can be very difficult to recognize in a clinical interview.3 Subtle manifestations of cataplexy may include head drop, sagging of the face or jaw, slurred speech, or buckling of the knees.1-3,15 It is important to probe for cataplexy in a clinical interview and to include the patient’s partner in the interview if possible.1,3 Also, some medications (eg, antidepressants) may suppress cataplexy1,15 and patients may have learned to avoid situations or emotions that may evoke a cataplexy attack.3

  What to know:

Cataplexy more commonly presents as partial attacks affecting only certain muscle groups rather than complete attacks involving collapse to the ground.2

Neck weakness, producing head drop, is a common manifestation of cataplexy, whereas facial weakness may lead to sagging of the jaw and dysarthria (eg, slurred speech).1-3,15 Commonly affected muscle groups include: arms and legs (eg, knees buckling); head and neck (eg, head dropping); face and jaw (eg, sagging, slurred speech, eyelid drooping). Although many emotions may potentially lead to cataplexy in narcolepsy, those associated with mirth (eg, laughing out loud, telling a joke, making a witty remark) are usually the most potent, and almost all patients with narcolepsy with cataplexy report some cataplexy episodes precipitated by emotions associated with laughter.1,15

  What to ask:

How often have you experienced weak knees/buckling of the knees or sagging of the jaw during emotions like laughing, happiness, or anger?4


Hypnagogic Hallucinations
  What is it:

Vivid dream-like experiences that occur at wake-sleep transitions.1

These hallucinations can be quite vivid and often cause fear and distress in patients.2,6 Life-like and often frightening, these hallucinations frequently combine visual, auditory, and tactile phenomena.1,2,6,16 Patients may visualize an animal or a threatening figure, hear the ringing of a phone, the sound of music, or spoken words, or perceive the sensation of falling or being touched, and may even describe an out-of-body experience.2,6 Hypnopompic hallucinations are similar but occur at the transitions from sleep to wake.2,6,16 

  Diagnostic challenge:

Hypnagogic hallucinations may occur in any sleep-deprived individual.5 In addition, patients are often reluctant to discuss these experiences unless asked specifically.5,6

Although hypnagogic hallucinations may occur in people without narcolepsy, they occur with greater frequency and intensity in people with narcolepsy.6

  What to know:

Patients may describe vivid dreams or nightmares, sometimes with realistic awareness of the presence of someone.1,2,7

These hallucinations can be quite vivid and often cause fear and distress in patients.2,6 Patients may describe these hallucinations as feeling the presence of a person in the room, falling, or hearing threatening words.2,7 Hallucinations are sometimes so frightening that patients become fearful of going to bed.5,6 Hypnagogic hallucinations may occur with sleep paralysis.2,5,6

  What to ask:

How often do you have vivid dream-like experiences at wake-sleep transitions?1


Excessive Daytime Sleepiness
  What is it:

Inability to stay awake and alert during the day, resulting in periods of irrepressible need for sleep or unintended lapses into drowsiness or sleep.1

Excessive daytime sleepiness is the cardinal and an essential symptom of narcolepsy, meaning that it is present in all patients with narcolepsy and is essential for the diagnosis.1 The excessive daytime sleepiness associated with narcolepsy can be disabling, reflecting a propensity to fall asleep in situations that can interfere with patients’ lives, or even in dangerous situations.1,2 It is typically the most disabling symptom of narcolepsy; it may be associated with sudden irresistible lapses into sleep, or “sleep attacks.”1 Sleep attacks may occur in active situations such as eating, walking, or talking.1,2,7

  Diagnostic challenge:

Patients may initially report only manifestations of excessive daytime sleepiness, such as tiredness, fatigue, difficulty concentrating, irritability, or other mood changes.8

Many patients are not able to accurately describe their excessive daytime sleepiness. Therefore, it is important to incorporate a sleepiness scale to help assess this important symptom.8

  What to know:

Excessive daytime sleepiness is most common in monotonous situations but may also occur in active situations such as eating or talking.1,2,7

Patients may also experience “sleep attacks,” the sudden, irresistible urge to sleep, even in active situations such as eating, walking, and talking.1,2,7 Many patients may describe repeated daytime naps throughout the day, which may be refreshing for only a short period of time.1,2 Some patients with excessive daytime sleepiness associated with narcolepsy may describe occasional automatic behaviors, during which they continue an activity without awareness.1,2 Examples of automatic behavior include writing gibberish or interrupting a conversation with a completely different topic.1

  What to ask:

How likely are you to doze or fall asleep in situations such as sitting and reading, sitting and talking with someone, or in a car while stopped in traffic for a few minutes?9

The Epworth Sleepiness Scale, or ESS, is a validated scale for assessing daytime sleepiness that can be used to assess an individual’s propensity to fall asleep in common situations.9 The ESS can be found on the Screening Tools page of this website and on the Resources page.


Sleep Paralysis
  What is it:

Disturbing temporary inability to move voluntary muscles or speak at sleep-wake transitions.1,2,5,6

Awareness is maintained,1,2,6 and like hypnagogic hallucinations, these can be frightening experiences.1,5,6 Despite being awake and conscious of the sleeping environment, it is impossible for individuals to move their limbs or even open their eyes during sleep paralysis.1 Sleep paralysis can be accompanied by a sensation of the inability to breathe normally.5,6

  Diagnostic challenge:

Like hypnagogic hallucinations, sleep paralysis is not specific to narcolepsy and may occur in any sleep-deprived individual.5

  What to know:

These episodes typically end spontaneously within 1-10 minutes, or can end when another person touches the patient.2,6 Sleep paralysis can occur with hypnagogic hallucinations.2,5,6

  What to ask:

How often do you experience disturbing feelings of being unable to move or speak when falling asleep or waking up?1,2,6


Sleep Disruption
  What is it:

Interruption of sleep by frequent awakenings and poor quality sleep.10

Because narcolepsy is a disorder of sleep-wake state instability,1,18,19 many patients may commonly report disruption of nighttime sleep.1,7,10

  Diagnostic challenge:

Patients with narcolepsy also frequently have comorbid sleep disorders such as obstructive sleep apnea or periodic limb movements of sleep.10-14

Awakenings may be increased in patients with comorbid sleep disorders, such as sleep apnea and periodic limb movement disorder.13,14 Sleep disruption can occur in the absence of comorbid conditions. In one study including 102 patients with narcolepsy, patients with only narcolepsy had a similar number of awakenings as patients with comorbid obstructive sleep apnea.17

  What to know:

Patients with narcolepsy may initiate sleep very quickly, but may report the inability to maintain continuous sleep.1

Sleep onset is rarely a problem, as patients with narcolepsy may initiate sleep very quickly.1 Patients may commonly report inability to maintain continuous sleep, with frequent awakenings1,7,10 and poor sleep quality.10 Sleep disruption may exacerbate excessive daytime sleepiness and may further contribute to a loss of control these patients have over their schedule.1,14

  What to ask:

Do you fall asleep easily but have difficulty staying asleep or experience poor quality sleep?1,7,10

To evaluate for possible sleep disruption associated with narcolepsy, consider asking patients to report their number of awakenings per night, the duration of awake time in bed, and their sleep quality.1,10


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