An Overview of Narcolepsy

Excessive Sleepiness May Be Due to a Neurologic Condition

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Narcolepsy was first described by the French physician Jean Gelineau in 1880, and even though it is thought to affect about 1 in 2,000 people, it is one of the least understood sleep disorders.

Narcolepsy can lead to profoundly disabling symptoms, ranging from sudden attacks of sleepiness to muscle weakness, called cataplexy, that may lead to a person collapsing on the floor.

Diagnosis of narcolepsy requires a medical history and physical exam, as well as studies to access a person's sleep patterns during the day and at night. The treatment of narcolepsy usually involves a combination of medication and behavior strategies, like maintaining a regular sleep schedule.

Symptoms

The symptoms of narcolepsy usually begin in a person's teens or early twenties, but they may rarely first occur in childhood or even late adulthood.

There are four main symptoms of narcolepsy—although, only one in three people with narcolepsy has all four.

Daytime Sleepiness

Every person with narcolepsy experiences excessive daytime sleepiness, where they doze off at random times during the day when they should be awake. Sometimes this occurs without much warning, which can, unfortunately, lead to injury.

Keep in Mind

People with narcolepsy do not sleep more than healthy individuals—their sleep-wake patterns are simply disrupted.

Cataplexy

Cataplexy occurs when a person experiences sudden, short-lived loss of voluntary muscle tone (weakness) while awake. This weakness is emotionally-triggered, meaning its onset occurs when a person is feeling a strong emotion, like laughter, anger, or surprise.

Important Point

Since cataplexy is not known to occur in any other disorder, its presence is strongly suggestive of a narcolepsy diagnosis.

The weakness of cataplexy usually begins in the face and then moves to the knees. It may result in jaw-dropping, head nodding, knees sagging, limping, and in severe cases, falling. The good news is that the weakness is transient, with episodes usually lasting from a few seconds to a few minutes.

Interestingly, the presence of cataplexy in a person with narcolepsy defines whether or not they have type 1 or type 2 narcolepsy. Type 1 narcolepsy means a person experiences cataplexy, whereas type 2 (which is less well studied) involves narcolepsy without cataplexy.

Hallucinations

People with narcolepsy may experience intense, vivid hallucinations while awake but transitioning to sleep (called hypnagogic hallucinations). These hallucinations occur as a result of the brain generating dreams while awake.

Definition

A hallucination means that a person may see, hear, or feel things that are not really there.

Sleep Paralysis

Sleep paralysis means that a person cannot move or speak for one to two minutes right after waking up. This may also happen just prior to falling asleep. Sometimes the paralysis is accompanied by hallucinations or a feeling of suffocation, which can be extremely frightening.

Other

In addition to the above symptoms, many people with narcolepsy suffer from psychiatric problems, like depression and/or anxiety. If you are experiencing symptoms of depression (for example, feeling sad all the time or losing interest in activities you once enjoyed) or experiencing symptoms of anxiety (for example, worrying all the time or enduring panic attacks) be sure to talk with your doctor.

Obesity is also common in narcolepsy and is believed to be related to hypocretin deficiency.

Cause

Narcolepsy appears to occur because of a loss of the chemical hypocretin (also called orexin) in an area of the brain called the hypothalamus. Hypocretin is thought to promote wakefulness and maintain normal muscle tone, so it makes sense that its loss would lead to sleepiness and the sudden weakness seen in cataplexy.

An Autoimmune Process

It is thought that the body's immune system, which typically is responsible for fighting infection, may target and destroy hypocretin-containing neurons (nerve cells), which research has found are lost in 85 to 95 percent of people with narcolepsy.

Why a person's immune system turns against these neurons in the brain remains unclear. Many experts suspect that an infection (typically a cold or flu) may trigger the body to react against itself in genetically-susceptible individuals.

Notable Finding

Interestingly, certain vaccines may play a role as well in the development of narcolepsy. In fact, an increased risk of narcolepsy was found following vaccination with Pandemrix, a monovalent H1N1 influenza vaccine produced for the 2009-2010 flu season and only used in Europe. Use of this vaccine has since been halted.

Besides autoimmunity, narcolepsy may also be caused by rare lesions within the brain that result because of tumors, strokes, or other inflammatory insults.

Finally, there is likely a genetic component to narcolepsy, as this disorder is found among family members. Although the environment plays a critical role, as research has found that only about 25 percent of identical twins will both have narcolepsy.

Diagnosis

If you believe you may be suffering from narcolepsy, your doctor, usually a sleep specialist, will first perform a medical history and physical exam. Then, various sleep tests may be recommended to clinch the diagnosis of narcolepsy or evaluate for other sleep disorders.

Medical History

During your appointment, the doctor will start by asking you several questions about your sleep.

Examples of such questions may include the following:

  • Do you feel rested in the morning, but then sleepy for the majority of the day?
  • Do you find yourself falling asleep at inappropriate times?
  • When you laugh or become angry, do you ever experience sudden muscle weakness?
  • When you wake up, are you ever not able to move or speak?

Answering "yes" to one or more these questions usually warrants further investigation into a possible diagnosis of narcolepsy.

Of course, in order to consider other diagnoses or causes behind your symptoms, your doctor will also ask questions, like:

  • Are you taking any medications to help you sleep or that make you tired? (this could indicate that a medication may be the culprit behind your daytime sleepiness)
  • Do you experience morning headaches and/or does your partner say you snore loudly? (these could be clues of an alternative diagnosis, like sleep apnea).

Physical Exam

In addition to a medical history, your doctor will perform a physical exam, which will include a neurologic exam, mostly to rule out other causes for daytime sleepiness or muscle weakness.

Sleep Tests

If your doctor is suspicious for a diagnosis of narcolepsy based on your history and exam, you will need to undergo further testing. Typically, your doctor will have you complete a sleep log or actigraphy in order to record how much sleep you are getting.

This will then be followed by an overnight sleep study called a polysomnogram (which is often normal in people with narcolepsy), followed by a study the next day called a multiple sleep latency test (MSLT), which is a daytime nap test.

A diagnosis of narcolepsy is strongly supported if, on the MSLT, a person falls asleep in less than eight minutes on average across all naps and enters REM sleep during two or more naps.

Interesting Fact

Most people without narcolepsy take longer than eight minutes to fall asleep during naps, and if they do sleep, they rarely enter REM sleep.

Lumbar Puncture

Used as a research tool or if a person's sleep studies are negative (but there is still a strong suspicion for narcolepsy), a lumbar puncture (spinal tap) may be performed. The purpose of the lumbar puncture is to evaluate the level of the chemical hypocretin in the cerebrospinal fluid (CSF), which is the fluid that bathes the brain and spinal cord.

Since the entire collection of 60,000 to 70,000 nerve cells in the hypothalamus (hypocretin-containing neurons) are permanently destroyed in a person with narcolepsy, the level of hypocretin detected in the cerebrospinal fluid (CSF) should eventually drop to zero.

Treatment

Narcolepsy is a chronic condition with no cure, as the destruction of hypocretin-containing cells is typically complete and the resulting deficit is permanent. Therefore, narcolepsy requires persistent treatment.

The good news is that behavior modifications, as well as different medications, can be used to treat the symptoms associated with narcolepsy.

Behavioral Modifications

Examples of behavior changes that can decrease the symptoms of narcolepsy include:

  • Avoiding medications or substances that make a person drowsy or sleepy (e.g., allergy medicines or alcohol
  • Moderating caffeine intake, as excessive caffeine intake can worsen insomnia, which can worsen daytime sleepiness
  • Maintaining a regular, sufficient sleep schedule (sleep deprivation can worsen narcolepsy symptoms)
  • Scheduling one to two naps during the day

It's also important for a person with narcolepsy to follow closely with his or her primary care physician. Weight problems and side effects from medications can be addressed and monitored.

Sometimes a referral to a mental healthcare professional is warranted—not only to address possible psychiatric conditions, like depression and anxiety, but also to cope with the daily life challenges of living with narcolepsy.

REM-Suppressing Medications

Cataplexy, sleep paralysis, and hypnagogic hallucinations occur during REM sleep, which can be strongly inhibited by the brain chemicals, norepinephrine and serotonin. Therefore, medications, like Effexor (venlafaxine) and Prozac (fluoxetine), that increase the brain levels of norepinephrine and serotonin can help reduce these symptoms of narcolepsy.

Stimulant Medications

Daytime sleepiness in narcolepsy can be treated with stimulant medications, such as:

Sodium Oxybate

Xyrem (sodium oxybate) is another medication used to reduce cataplexy, usually more severe cases. It can also be used to treat daytime sleepiness.

On the Horizon

It's good to remain hopeful about the future treatment of narcolepsy. New therapeutics may be able to prevent, slow, or reverse the destruction of the hypocretin-containing cells in susceptible individuals. Regeneration of this population of brain cells with stem cell transplants may also eventually be possible.

Though these interventions are still distant on the horizon, there remains the possibility that one day, narcolepsy may ultimately go away in those who are afflicted with it.

A Word From Verywell

If you suffer from narcolepsy, it is important to speak with a sleep specialist who can tailor the treatment to your specific, unique needs. Though disability often persists, patients with narcolepsy are usually able to preserve many daily functions and optimize their quality of life through a combination of careful behavior changes and medication.

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