Specialist Advice — 9 minutes

What is narcolepsy?

Sleep care team
Sleep care team
info@biron.com

Narcolepsy is a neurological disorder that affects the sleep-wake cycle, in particular by disturbing dream sleep. To understand narcolepsy, we must first know that during our dreams we are paralyzed, so that we do not try acting them out. The narcoleptic person, when awake and rested, may suddenly fall asleep (sleep attack), start dreaming (hallucinations), become paralyzed (cataplexy), or remain unable to move after waking (sleep paralysis).

This rare disease, which affects about 0.04% of the population,[1] varies considerably in intensity and the expression of its symptoms.

Causes of narcolepsy

There are two distinct types of narcolepsy: types 1 and 2.

Type 1 narcolepsy is characterized by the presence of cataplexy and the absence of hypocretin (also called “orexin”), a brain neurotransmitter responsible for wakefulness. Researchers believe that an autoimmune reaction completely destroys hypocretin-producing nerve cells due to genetic and environmental factors.[2]

In contrast, people with type 2 narcolepsy do not have cataplexy. Hypocretin is present in their brains, but in lower amounts.

Finally, narcolepsy can also be caused by a brain injury such as concussion, or neurological diseases affecting the regions that regulate wakefulness and REM sleep.

Symptoms

All people living with narcolepsy suffer from excessive daytime sleepiness and sleep attacks. Between these episodes, these individuals have a normal level of alertness, especially if they are involved in activities that require their attention.

Cataplexy, which occurs in type 1 narcoleptics, causes weakness in a limited number of muscles or, in more severe attacks, almost complete paralysis of the muscles. This can lead to a total collapse of the body, where people are unable to move, speak or keep their eyes open, even if they remain conscious. Cataplexy is often triggered by sudden strong emotions such as laughter, fear, anger, stress or excitement.

Sleep paralysis is similar to cataplexy, except that it usually occurs at the time of falling asleep or waking up. Even when severe, cataplexy and sleep paralysis do not cause lasting effects. Once the episode is over, the person quickly regains the ability to move and speak.

Narcoleptics sometimes suffer from hypnagogic and hypnopompic hallucinations, i.e. visual, auditory or tactile sensations that occur when falling asleep or waking up. These vivid and sometimes frightening images may be accompanied by sleep paralysis.

Despite their excessive daytime sleepiness, narcoleptics often have poor quality, fragmented sleep. They may also suffer from a variety of sleep disorders, such as insomnia, nightmares or night terrors, sleep apnea, sleepwalking and periodic leg movements.

Automatic behaviors are also a symptom of narcolepsy. These are brief episodes of sleep during a routine activity (e.g. writing or driving). The person automatically continues this activity without being aware of what they are doing, which impairs their performance. For example, writing may become a scribble, or the person may put things away in unusual places and cannot find them afterwards.

Diagnosis

The health care professional first ensures that the patient is sleeping regularly and sufficiently by means of an actigraphy and/or a sleep diary in which the patient records the length and quality of their sleep and the level of their sleepiness.

The professional then proceeds with a polysomnography to rule out other sleep disorders, followed the next day by a multiple sleep latency test (MSLT), in which the patient takes four or five 20-minute naps at two-hour intervals. Typically, narcoleptics fall asleep in less than eight minutes on average, experiencing dreams within less than 15 minutes during at least two of the five naps.

Diagnosis of type 1 narcolepsy can also be confirmed by measuring the level of hypocretin. However, this test requires a lumbar puncture, which is a fairly invasive procedure.

Treatment

Although narcolepsy cannot be cured, some symptoms can be relieved with lifestyle changes and medication. For example, strategically planned preventive naps help prevent sleep attacks. Medications such as psychostimulants are recommended to reduce daytime sleepiness. One such drug is modafinil, which is less addictive than amphetamine derivatives. Antidepressants are also prescribed to reduce cataplexy.

Other avenues are also being explored to optimize the treatment of narcolepsy.[3] For example, sodium oxybate, a central nervous system depressant, and pitolate, which acts on histamine production, may reduce both daytime sleepiness and the number of cataplexy episodes.

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Sources3
  1. OHAYON, Maurice M. “Epidemiological Overview of Sleep Disorders in the General Population,” Sleep Medicine Research, Vol. 2, #1, pp. 1-9, 2011, https://www.sleepmedres.org/journal/view.php?number=14.
  2. JACOB, Louis and Yves DAUVILLIERS. “La narcolepsie avec cataplexie : une maladie auto-immune?” Médecine/sciences, Vol. 30, #12, December 2014, https://www.medecinesciences.org/en/articles/medsci/full_html/2014/12/medsci20143012p1136/medsci20143012p1136.html.
  3. THORPY, M. J. “Recently Approved and Upcoming Treatments for Narcolepsy,” CSN Drugs, Vol. 34, #1, pp. 9-27, January 2020, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6982634/.