Narcolepsy Causes, Signs, Symptoms, Diagnosis, Treatment, Prevention

Narcolepsy Causes, Signs, Symptoms, Diagnosis, Treatment, Prevention


What Is Narcolepsy?


Narcolepsy is a chronic sleep disorder with no known cause. The main characteristic of narcolepsy is excessive and overwhelming daytime sleepiness, even after adequate nighttime sleep. A person with narcolepsy is likely to become drowsy or to fall asleep, often at inappropriate times and places. Daytime sleep attacks may occur with or without warning and may be irresistible. These attacks can occur repeatedly in a single day. Drowsiness may persist for prolonged periods of time. In addition, nighttime sleep may be fragmented with frequent wakenings. 

Narcolepsy Causes, Signs, Symptoms, Diagnosis, Treatment, Prevention


Three other classic symptoms of narcolepsy, which may not occur in all patients, are:
  • Cataplexy: sudden episodes of loss of muscle function, ranging from slight weakness (such as limpness at the neck or knees, sagging facial muscles, or inability to speak clearly) to complete body collapse. Attacks may be triggered by sudden emotional reactions such as laughter, anger, or fear and may last from a few seconds to several minutes. The person remains conscious throughout the episode.
  • Sleep paralysis: temporary inability to talk or move when falling asleep or waking up. It may last a few seconds to minutes.
  • Hypnagogic hallucinations: vivid, often frightening, dream-like experiences that occur while dozing or falling asleep.
Daytime sleepiness, sleep paralysis, and hypnagogic hallucinations can also occur in people who do not have narcolepsy. 

In most cases, the first symptom of narcolepsy to appear is excessive and overwhelming daytime sleepiness. The other symptoms may begin alone or in combination months or years after the onset of the daytime sleep attacks. There are wide variations in the development, severity, and order of appearance of cataplexy, sleep paralysis, and hypnagogic hallucinations in individuals. Only about 20 to 25 percent of people with narcolepsy experience all four symptoms. The excessive daytime sleepiness generally persists throughout life, but sleep paralysis and hypnagogic hallucinations may not. 

The symptoms of narcolepsy, especially the excessive daytime sleepiness and cataplexy, often become severe enough to cause serious disruptions in a person's social, personal, and professional lives and severely limit activities.

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How common is narcolepsy?


The prevalence of narcolepsy is similar to that of Parkinson's disease and multiple sclerosis. In the United States, the National Institute of Neurological Disorders and Stroke estimates narcolepsy affects one in every 2,000 people. However, in some countries (for example, Israel), the prevalence of narcolepsy is much lower (one per 500,000) while in other countries (for example, Japan), it is much higher (one per 600). The American Sleep Association estimates that approximately 125,000 to 200,000 Americans suffer from narcolepsy, but only fewer than 50,000 are properly diagnosed.

Narcolepsy often remains undiagnosed or misdiagnosed for several years. This may occur because physicians do not consider the diagnosis of narcolepsy frequently enough. They may think of narcolepsy only in people who have the main symptom of excessive daytime sleepiness. Narcolepsy may not be considered in the evaluation of patients who come to doctors complaining of fatigue, tiredness, or problems with concentration, attention, memory, and performance, and other illnesses (seizures, mental illness, etc.).

What causes narcolepsy?


Advances have been made in the last few years in determining the cause of narcolepsy. The newest discovery has been the finding of abnormalities in the structure and function of a particular group of nerve cells, called hypocretin neurons, in the brains of patients with narcolepsy. These cells are located in a part of the brain called the hypothalamus and they normally secrete neurotransmitter substances (chemicals released by nerve cells to transmit messages to other cells) called hypocretins.

Abnormalities in the hypocretin system may be responsible for the daytime sleepiness and abnormal REM sleep found in narcolepsy.

Experiments in dogs and mice with narcolepsy point to an abnormal hypocretin system as a cause for the development of their narcolepsy. People with narcolepsy have been found to have a markedly decreased number of hypocretin nerve cells in the brain. They also have a decreased level of hypocretins in the cerebrospinal fluid (the fluid that surrounds the brain and the spinal cord).

Narcolepsy is associated with a specific type of human leukocyte antigen (HLA). HLAs are genetically determined proteins on the surface of white blood cells. They are a part of the body's immune (defense) system. The finding of a very high HLA-association in narcolepsy led to the proposal that narcolepsy is an autoimmune disease, similar to other HLA-associated diseases such as multiple sclerosis and ankylosing spondylitis.

It is theorized that an autoimmune reaction causes the loss of nerve cells in the brain in patients with narcolepsy. The environment (for example, infection or trauma) might trigger an autoimmune reaction where normal brain cells are attacked by the body's own immune system. As a result, the neurons are damaged and ultimately destroyed, and they and their neurotransmitter chemicals disappear. Whether narcolepsy is an autoimmune disease remains to be proven.

The role of heredity in humans with narcolepsy is not completely understood. No consistent pattern of heredity has been recognized in families so far. It is estimated that relatives of patients with narcolepsy may have a higher predisposition to develop narcolepsy or sleep-related abnormalities, such as increased daytime sleepiness, increased REM sleep, or others. In dogs with narcolepsy, the disease is inherited in a predictable pattern. In these animals, the narcolepsy is caused by a mutation in a particular gene that is normally responsible for producing a receptor (binder) in the brain for the hypocretin neurotransmitter.

Signs and symptoms of narcolepsy



Narcolepsy Causes, Signs, Symptoms, Diagnosis, Treatment, Prevention


Most sufferers experience their first symptoms of narcolepsy between the ages of 10 and 25. Symptoms can vary greatly from one person to another, but the main narcolepsy symptoms are excessive daytime sleepiness (with or without sudden sleep episodes) and abnormal REM sleep. Other symptoms of narcolepsy may be related to your abnormal REM sleep, including hallucinations, sleep paralysis, and cataplexy (sudden loss of muscle control).


Two of the most common narcolepsy symptoms—excessive daytime sleepiness and cataplexy—are often connected to your emotional state. You may tend to exhibit these symptoms when you experience intense emotions, such as laughter, sadness, surprise, or frustration.

Common narcolepsy symptoms include:


  • Cataplexy (loss of muscle control). Often, narcolepsy may cause you to have a sudden loss of muscle control while awake, usually triggered by strong emotions, such as laughing or crying.
  • Hallucinations. Some people with narcolepsy experience vivid, sometimes frightening, visual or auditory sensations while falling asleep or upon awakening.
  • Sleep paralysis. You may be unable to move or talk at the beginning or end of sleep.
  • Microsleep is a very brief sleep episode during which you continue to function (talk, put things away, etc.), and then awaken with no memory of the activities.
  • Nighttime wakefulness. If you suffer from narcolepsy, you may have periods of wakefulness at night with hot flashes, elevated heart rate, and sometimes intense alertness.
  • Rapid entry into REM sleep. Narcoleptics have unique sleep cycles where he or she may enter the REM or dream phase of sleep right after falling asleep, whereas most people take about 90 minutes to enter REM. Therefore, you’ll experience the characteristics of REM sleep (vivid dreams and muscle paralysis) at the beginning of sleep, even if that sleep is during the day.

What Happens in Narcolepsy?


Normally, when an individual is awake, brain waves show a regular rhythm. When a person first falls asleep, the brain waves become slower and less regular. This sleep state is called non-rapid eye movement (NREM) sleep. After about an hour and a half of NREM sleep, the brain waves begin to show a more active pattern again, even though the person is in deep sleep. This sleep state, called rapid eye movement (REM) sleep, is when dreaming occurs. 

In narcolepsy, the order and length of NREM and REM sleep periods are disturbed, with REM sleep occurring at sleep onset instead of after a period of NREM sleep. Thus, narcolepsy is a disorder in which REM sleep appears at an abnormal time. Also, some of the aspects of REM sleep that normally occur only during sleep--lack of muscle tone, sleep paralysis, and vivid dreams--occur at other times in people with narcolepsy. For example, the lack of muscle tone can occur during wakefulness in a cataplexy episode. Sleep paralysis and vivid dreams can occur while falling asleep or waking up. 

How Is Narcolepsy Diagnosed?


A physical exam and exhaustive medical history are essential for proper diagnosis of narcolepsy. However, none of the major symptoms is exclusive to narcolepsy. Several specialized tests, which can be performed in a sleep disorders clinic or sleep lab, usually are required before a diagnosis can be established. Two tests that are considered essential in confirming a diagnosis of narcolepsy are the polysomnogram (PSG) and the multiple sleep latency test (MSLT).

Narcolepsy Causes, Signs, Symptoms, Diagnosis, Treatment, Prevention

The PSG is an overnight test that takes continuous multiple measurements while a patient is asleep to document abnormalities in the sleep cycle. A PSG can help reveal whether REM sleep occurs at abnormal times in the sleep cycle and can eliminate the possibility that an individual's symptoms result from another condition.

The MSLT is performed during the day to measure a person's tendency to fall asleep and to determine whether isolated elements of REM sleep intrude at inappropriate times during the waking hours. As part of the test, an individual is asked to take four or five short naps usually scheduled two hours apart.

Narcolepsy treatment


Although no cure yet exists for narcolepsy, a combination of treatments can help control your narcolepsy symptoms and enable you to enjoy many normal activities. The treatment that works best for you will vary according to your specific narcolepsy symptoms, but will likely include a combination of counseling, medication, and lifestyle changes.

In addition to drug therapy, an important part of treatment is scheduling short naps (10 to 15 minutes) two to three times per day to help control excessive daytime sleepiness and help the person stay as alert as possible. Daytime naps are not a replacement for nighttime sleep. 

Ongoing communication among the physician, the person with narcolepsy, and family members about the response to treatment is necessary to achieve and maintain the best control. 

Narcolepsy treatment: counseling and support groups


It’s very common for those with narcolepsy to suffer from depression. Many symptoms of narcolepsy—particularly sleep attacks and cataplexy—can cause great embarrassment and wreak havoc on your ability to live a normal life. These episodes can be frightening, and you may become depressed because of the sudden lack of control. Fear of falling asleep or of sudden collapse forces some people to become reclusive and withdrawn. Reaching out to a psychologist, counselor, or narcolepsy support group can help you cope with the effects of the disorder.

Reaching out may seem overwhelming at first, but being with others who face the same problems can help reduce your sense of isolation and remove any stigma you may feel. It can also be inspiring to share experiences and learn how others have coped with his or her symptoms of narcolepsy.

Narcolepsy Causes, Signs, Symptoms, Diagnosis, Treatment, Prevention

Lifestyle changes to ease the symptoms of narcolepsy


Making healthy lifestyle changes can help you manage narcolepsy symptoms, in conjunction with counseling and support, and any recommendations from your doctor. Daytime habits—such as exercise, diet, and how you manage stress—play a large role in helping you maintain a healthy sleep-wake cycle. It’s important to follow a regular sleep schedule, a relaxing bedtime routine, and take practical steps to counter the effects of narcolepsy during the day.

Combining the various self-help treatments can help to not only improve your daytime alertness but also help reduce the symptoms of narcolepsy.

Medications for the treatment of narcolepsy


Medication can be helpful in treating the major symptoms of narcolepsy: sleepiness and cataplexy. 

Commonly prescribed drugs for narcolepsy are stimulants, antidepressants, and sodium oxybate. All medications have side effects so be sure to check with your doctor first. Even if your narcolepsy symptoms require the use of prescription medication, experts recommend combining a drug regimen with lifestyle changes and counseling or therapy.

Common medications used to treat narcolepsy symptoms include:


Stimulants


Stimulants are the mainstay of drug treatment for narcolepsy. These include modafinil (Provigil), a stimulant used during the day to promote wakefulness and alertness. Side effects of modafinil may include headache, nausea, dry mouth, and diarrhea. Psychiatric side effects, such as anxiety, mania, hallucinations, and suicidal thinking have also been reported, so the drug should be avoided if you have a history of depression, mania, or psychosis.

Sodium oxybate (Xyrem)


This strong drug may be prescribed if you have severe cataplexy. Sodium oxybate is also known as GHB, or the "date rape drug," but is considered safe for treating narcolepsy when used responsibly to promote sound sleep, diminish daytime sleepiness, and reduce incidences of cataplexy. However, the side effects can be serious and may include nausea, bed-wetting, and worsening of sleepwalking. Too high a dose can even lead to difficulty breathing, coma, and death.

Antidepressants


Selective serotonin reuptake inhibitors (SSRIs) used to treat depression may also be used to help suppress REM sleep, and alleviate symptoms of cataplexy, hallucinations, and sleep paralysis. These include fluoxetine (Prozac), sertraline (Zoloft), and newer antidepressants such as venlafaxine (Effexor). While the most common side effects of antidepressants include decreased sexual desire, digestive problems, restlessness, headache, and insomnia, there can also be dangerous side effects.

How to Prevent Narcolepsy


At this time there are no known ways to prevent the development of Narcolepsy. If you have narcolepsy, there are some lifestyle changes you can make to reduce your chances of having an attack of narcolepsy.

What Is Being Done To Better Understand Narcolepsy?


Studies supported by the National Institutes of Health (NIH) are trying to increase understanding of what causes narcolepsy and improve physicians' ability to detect and treat the disease. Scientists are studying narcolepsy patients and families, looking for clues to the causes, course, and effective treatment of this sleep disorder. Recent discovery of families of dogs that are naturally afflicted with narcolepsy has been of great help in these studies. Some of the specific questions being addressed in NIH-supported studies are the nature of genetic and environmental factors that might combine to cause narcolepsy and the immunological, biochemical, physiological, and neuromuscular disturbances associated with narcolepsy. Scientists are also working to better understand sleep mechanisms and the physical and psychological effects of sleep deprivation and to develop better ways of measuring sleepiness and cataplexy.

How Can Individuals and Their Families and Friends Cope With Narcolepsy?


Learning as much about narcolepsy as possible and finding a support system can help patients and families deal with the practical and emotional effects of the disease, possible occupational limitations, and situations that might cause injury. A variety of educational and other materials are available from sleep medicine or narcolepsy organizations. Support groups exist to help persons with narcolepsy and their families. 

Individuals with narcolepsy, their families, friends, and potential employers should know that:
  • Narcolepsy is a life-long condition that requires continuous medication.
  • Although there is not a cure for narcolepsy at present, several medications can help reduce its symptoms.
  • People with narcolepsy can lead productive lives if they are provided with proper medical care.
  • If possible, individuals with narcolepsy should avoid jobs that require driving long distances or handling hazardous equipment or that require alertness for lengthy periods.
  • Parents, teachers, spouses, and employers should be aware of the symptoms of narcolepsy. This will help them avoid the mistake of confusing the person's behavior with laziness, hostility, rejection, or lack of interest and motivation. It will also help them provide essential support and cooperation.
  • Employers can promote better working opportunities for individuals with narcolepsy by permitting special work schedules and nap breaks.