Cataplexy is a sudden, brief loss of voluntary muscle tone triggered by strong emotions such as laughter.

The condition is most commonly associated with narcolepsy, a sleep disorder that is thought to affect between 135,000 and 200,000 people in the United States.

Cataplexy occurs during waking hours. During a mild attack, there may be a barely visible weakness in a muscle, such as drooping of the eyelids. A more severe episode may involve a total body collapse.

Although it is a different condition, cataplexy is sometimes misdiagnosed as a seizure disorder.

There is no cure for cataplexy, but it can be managed with medications and modification of potential triggers.

Fast facts on cataplexy

Here are some key points about cataplexy. More detail is in the main article.

  • During an episode of cataplexy, an individual is awake but temporarily paralyzed.
  • Cataplexy is worsened by fatigue and strong emotion and affects males and females equally.
  • Cataplexy is linked to narcolepsy and can occur after suddenly stopping an antidepressant medication.
  • Sodium oxybate is approved by the U. S. Food and Drug Administration (FDA) for the treatment of cataplexy

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A person with cataplexy may collapse temporarily as a result of excitement, laughter, or strong emotions.

Cataplexy is a sudden loss of muscle control, typically on both sides of the body, triggered by strong, often pleasant emotions.

Laughter is the most typical trigger, but other triggers may include happiness, excitement, annoyance, surprise, fear, or a stressful event.

Cataplexy is most often associated with narcolepsy, but it can occur with other rare disorders such as Niemann-Pick type C disease, Prader-Willi syndrome and Wilson's disease.

Occasionally, cataplexy can be seen in other medical conditions including stroke, multiple sclerosis, head injury and encephalitis.

The duration of a cataplexy attack is brief, generally lasting anywhere from a few seconds to a few minutes — usually less than 2 minutes — followed by a rapid return of normal muscle tone and function.

The REM sleep disassociation hypothesis suggests that cataplexy is the muscle paralysis that normally occurs during REM sleep intruding into waking hours.

The exact underlying cause of this intrusion is unknown, but a loss of neurons that produce hypocretin (also known as orexin) is thought to be a major contributing factor. Hypocretin is a neurotransmitter involved in the promotion of wakefulness within the sleep/wake cycle,

People with cataplexy have been found to have a certain human leukocyte antigen, variations in T-cell receptors, or dysfunctional immune system responses to certain antigen exposures. It is thought that narcolepsy may be an autoimmune disorder, but more research is needed.

A study published in the Journal of Clinical Investigation in 2010 revealed that the loss of hypocretin is caused by an autoimmune response targeting tribbles homolog 2 (trib 2) autoantigens. This autoimmune response causes trib 2 antibodies to form, which target and kill the neurons in the brain that produce hypocretin.

The frequency of cataplectic episodes varies from less than one per year to several per day. On average, a person with cataplexy will experience one or more episodes each week.

Symptoms of cataplexy associated with narcolepsy often begin in childhood and young adulthood, between the ages of 7 and 25 years, but it can start at any time.

Cataplectic attacks can vary widely. They may be mild and barely noticeable or severe with full body collapse.

Symptoms of a cataplectic episode may include:

  • facial twitching, flickering, or grimacing
  • unusual tongue movements
  • jaw tremor
  • dropping the head or jaw
  • knee trembling or buckling
  • drooping eyelid
  • speech difficulty

A person may collapse and be unable to move.

The episode usually lasts a few minutes or less and then passes without intervention. However, it is important to make sure the person will not hurt themselves if they collapse to a fall.

An individual experiencing cataplexy remains conscious, is able to breathe, and can move their eyes.

Tests can help diagnose narcolepsy with cataplexy, but a diagnosis is also based on the patient's description of events and history.

Often, an individual complains to a doctor about excessive daytime sleepiness (EDS) with a persistent background feeling of sleepiness during waking hours. EDS is commonly the first symptom of narcolepsy. However, if cataplexy occurs with EDS, narcolepsy is likely to be present.

Individuals who have EDS or symptoms of cataplexy should see their medical provider.

A sleep study (a polysomnogram) will most likely be ordered by the provider, followed by a Multiple Sleep Latency Test (MSLT), a series of five naps scheduled to be taken over the course of a day.

Carrying out the MSLT the day after polysomnography enables doctors to find out whether or not the sleep obtained the previous night has any effect on daytime napping.

There is no cure for cataplexy, and treatment is symptom management with good sleep hygiene practices and the use of medication as necessary.

Additionally, safety measures should be put in place to avoid serious injury that can result from falls.

Good sleep hygiene practices include:

  • keeping a consistent sleep schedule, including getting up and going to bed at the same time every day, even on weekends or during vacations
  • striving for at least 7 to 8 hours of sleep, or the amount that normally makes you feel refreshed
  • making the bedroom quiet and relaxing and keeping it at a comfortable, cool temperature
  • limiting exposure to light in the evenings
  • exercising regularly and maintaining a healthful diet
  • avoiding a large meal before bedtime and opting for a light, healthful snack if necessary
  • avoiding caffeine in the late afternoon or evening
  • avoiding alcohol
  • scheduling one or more short naps during the day.

Sodium oxybate at doses between 6 and 9 grams (g) nightly is the medication approved by the U.S. Food and Drug Administration (FDA) for the treatment of cataplexy. Sodium oxybate is effective in reducing both the frequency and intensity of attacks.

Possible adverse effects are dizziness, headache, and nausea. This medication should not be used in conjunction with alcohol or any other central nervous system (CNS) depressant due to the risk of respiratory depression and other significant CNS depressant effects.

Other medications that may help control symptoms are antidepressants. These include venlafaxine, a serotonin-noradrenaline reuptake inhibitor (SNRI) antidepressant, and tricyclic antidepressants such as clomipramine, imipramine, and desipramine.

However, evidence supporting the use of antidepressants for cataplexy is varied. In addition, abrupt withdrawal of venlafaxine can potentially cause rebound cataplexy.

In regards to safety, even if an individual senses the onset of an episode, injury is very possible with cataplexy.

To help avoid injury from occurring with cataplexy:

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Injury can occur if a person falls suddenly.

  • Assess for and be aware of potential dangers such as glass, sharp edges, and heights.
  • Practice relaxation and stress management techniques.
  • Avoid sleep deprivation.
  • Avoid situations that are likely to evoke strong emotions, or prepare ahead of time by sitting down or having a companion nearby.
  • Do not drive a car or operate heavy machinery until cleared by a medical provider.
  • Enlist the help of significant others and friends, and educate them on the seriousness of the disorder.

Cataplexy is a transient, sudden loss of voluntary muscle control brought on by a strong emotional trigger such as laughing or excitement. Cataplexy is almost always associated with narcolepsy.

There is no cure, but education, sleep hygiene practices, and prescription medication can help people with this condition enjoy a better quality of life.