Narcolepsy is a type of sleep disorder that causes patients to fall asleep suddenly, often at unexpected moments. It is a chronic central nervous system (CNS) disorder triggered by disturbances in the chemicals that regulate sleep-wake cycles in the brain.
Patients with narcolepsy feel drowsy much of the time and generally find it difficult to remain awake for extended periods. Although the exact cause is unknown, researchers believe that a combination of genetics and a trigger (such as a virus) cause the condition to develop. Narcolepsy can strike at any age, but most often develops between the ages of 10 and 25 and affects both sexes equally.
Excessive daytime drowsiness, the main symptom of narcolepsy, may be present for years before the condition is diagnosed. In addition to drowsiness, other symptoms commonly associated with narcolepsy include:
- Cataplexy. A sudden loss of muscle tone that may appear similar to a seizure.
- Sleep paralysis. A less frequent phenomenon marked by a temporary inability to move.
- Hypnagogic or hypnopompic hallucinations. Occur when patients are partially awake, causing them to have intense, frightening dreams that they perceive as reality.
- Automatic behavior. Occurs when patients continue to function as if awake during a sleep episode.
Patients typically seek medical care when they find that overwhelming drowsiness is causing them to fall asleep at inappropriate times or preventing them from functioning effectively. If a physician determines that narcolepsy is a likely diagnosis, the patient may be referred to a sleep specialist. The patient may fill out written evaluations that can reveal the presence of narcolepsy. In most cases, the patient’s sleeping patterns will be observed overnight in a sleep center to identify the specific changes in sleep patterns.
There is no cure for narcolepsy. However, medications and lifestyle changes can help patients to manage their symptoms and to lead full lives. Patients with narcolepsy are encouraged to talk to employers or teachers about their condition and ways to accommodate their needs. They should also take extra precautions to ensure that they are not hurt when a sudden episode of sleep strikes.
Narcolepsy is a chronic central nervous system (CNS) disorder that causes patients to suddenly fall asleep, often at unexpected moments. The sleep disorder is the result of a malfunction in the brain that prevents the proper regulation of sleep-wake cycles.
Patients with narcolepsy feel drowsy much of the time and generally find it difficult to remain awake for extended periods. Though they do not sleep more often than other people do, their bodies are unable to properly control the normal boundaries between sleeping and waking. Narcolepsy can be hazardous if a patient falls asleep while driving or climbing stairs.
There are four stages of non-rapid eye movement sleep that progress from light to deep. Following these stages is rapid eye movement (REM) sleep, a stage in which a person’s muscles are temporarily paralyzed and dreaming occurs. Initially, brain waves slow down for an hour or two before brain activity picks up again, leading to REM sleep. People who are asleep typically alternate between non-REM sleep and REM sleep throughout the night.
In contrast, people with narcolepsy quickly fall into REM sleep, often at unexpected moments. They also experience symptoms that occur in most people at other times of the sleep cycle. These include a relaxation of muscle tone (cataplexy), a temporary inability to move (sleep paralysis) and intense dreaming.
People with narcolepsy may also have other sleep disorders such as sleepwalking and/or mood disorders such as depression.
Patients may go many years before realizing that they have developed narcolepsy. They accept the daytime drowsiness as a part of life, not realizing it may be a more serious condition. Many do not seek treatment until other more disturbing symptoms such as cataplexy appear. Narcolepsy is incurable. However, effective forms of treatment can help patients to control their symptoms and to live full lives
Potential causes of narcolepsy
The precise causes of narcolepsy remain unclear. Researchers believe that a combination of genetics and a trigger (such as a virus) may alter chemicals that regulate sleep. For example, the neurotransmitter acetylcholine (a chemical involved in the transmission of nerve impulses in the body) appears to be excessively activated in patients with narcolepsy. There may also be a deficiency of the neurotransmitter known as hypocretin or orexin, which modulates activity in the part of the brain known as the hypothalamus, helping to awaken people and keeping them alert.
Other researchers have found that people who have narcolepsy may have fewer neurons in the brain that affect the transitions between sleeping and waking.
Narcolepsy can strike at any age, but most often develops between the ages of 10 and 25. It affects both sexes equally. Narcolepsy does not typically run in families despite the fact that researchers believe genetics are partially responsible for the condition.
Signs and symptoms of narcolepsy
The chief symptom associated with narcolepsy is a consistent and overwhelming sense of daytime drowsiness that causes people to suddenly fall asleep at any point. Such drowsiness is often the first indicator that a person is developing narcolepsy. Patients may nod off regardless of their circumstances and may remain asleep for anywhere from a few minutes to an hour.
Patients typically fall asleep after a meal or after engaging in low-stimulation activities (e.g., reading, attending a classroom lecture), but sudden sleep can strike at any time. It is common for someone with narcolepsy to fall asleep while in the middle of a task or a conversation. Patients often dream during this sleep. When they awaken, they usually feel rested but are tired again within a few hours.
People with narcolepsy often experience cataplexy, a sudden, uncontrollable loss of muscle tone that may appear similar to a seizure. Subtle symptoms of cataplexy may include slurred speech, sagging jaw and drooping eyelids. More severe symptoms may include buckling knees and even physical collapse. Episodes last for a few seconds to several minutes. Cataplexy may be triggered by intense emotions such as anger. Up to 70 percent of narcoleptic patients experience this symptom, according to the National Sleep Foundation(NSF). However, its frequency varies widely. For example, cataplexy may strike some patients several times over the course of each day, whereas other patients experience just a couple of episodes each year. Cataplexy does not involve loss of consciousness.
Sleep paralysis is a less frequent phenomenon marked by a temporary inability to speak or move. It usually occurs while the patient is falling asleep or just after the patient wakes up, and it lasts for 10 minutes or less. Patients may also feel as though they are unable to breathe during an episode of sleep paralysis.
Hypnagogic hallucinations may occur when a patient quickly falls into REM sleep. Hypnopompic hallucinations occur as the patient is awakening. Patients in these states remain partially awake, causing them to have intense, frightening dreams that they perceive as reality. These dreams may involve a blending of dream material with elements that are actually present in the patient’s environment.
Up to 60 percent of narcoleptic patients experience sleep paralysis, hypnagogic hallucinations or both, according to the NSF. When both conditions occur together, patients have the terrifying sensation of seeing hallucinations while being unable to move or speak.
Occasionally, patients may continue to function normally during a sleep episode. However, they awaken and have no memory of their preceding activities or conversations. This automatic behavior occurs in up to 80 percent of narcoleptic patients, according to the NSF.
Restless sleep during overnight hours and visual disturbances (such as blurred vision and droopy eyelids) are other symptoms often associated with narcolepsy.
In many cases, the symptoms associated with a patient’s narcolepsy will wax and wane over time. However, symptoms rarely disappear completely. The exception is cataplexy, which may subside over time.
Patients with narcolepsy may also experience other problems associated with their condition. Lack of sleep can cause patients to become lethargic and may affect work or school performance. Lower sex drive and impotence may also result from this condition.
Sudden attacks of sleep can also present dangers if they occur at particularly undesirable times, such as when a person is driving a car or preparing food over a hot stove.
Diagnosis methods for narcolepsy
Patients will typically seek medical care when they find that overwhelming drowsiness is causing them to fall asleep at inappropriate times or preventing them from functioning effectively. In many cases, patients with narcolepsy go undiagnosed for many years, believing that their daytime drowsiness is normal, and do not seek medical assistance until symptoms such as cataplexy (a sudden, uncontrollable loss of muscle tone) occur.
Before diagnosing narcolepsy, a physician will perform a complete physical examination and compile a thorough medical history. Diagnosing narcolepsy can be difficult because symptoms related to the disorder mimic those of other conditions that may disrupt patterns of consciousness. These include depression, seizure disorders, fainting and simple tiredness resulting from inadequate sleep. In addition, other sleep disorders – such as sleep apnea (temporary cessation of breathing during sleep), insomnia (inability to sleep) or restless leg syndrome (sleep disorder characterized by leg discomfort during sleep) – can cause drowsiness similar to that experienced during narcolepsy.
If the physician determines that narcolepsy is a likely diagnosis, the patient may be referred to a sleep specialist. Patients may be asked to complete the Epworth Sleepiness Scale, in which they will be asked about a number of day-to-day situations and whether or not those circumstances typically make them sleepy. Another diagnostic tool called the Stanford Narcolepsy Questionnaire can provide important information about a patient’s narcolepsy in general and cataplexy in particular.
In many cases, patients will be asked to stay overnight at a sleep center and participate in a sleep study that allows experts to closely monitor their sleep habits. Prior to the visit, patients may be asked to keep a diary that tracks their sleep patterns for a week or two.
On the night of the visit to the sleep center, electrodes are placed on the patient’s scalp and other body parts as part of a procedure known as a polysomnogram. During this test, the electrical activity or movement of the heart, brain, muscles and eyes are measured. A polysomnogram helps indicate how much time elapses before a patient falls asleep. Shorter periods may indicate narcolepsy.
Patients may also undergo a multiple sleep latency test, which measures the length of time it takes a patient to fall asleep during the day. As part of this test, the patient is asked to take four or five naps spaced two hours apart. Experts observe how long it takes the patient to enter into rapid eye movement (REM) sleep. Patients with narcolepsy typically fall asleep much faster (less than five minutes) than those who do not have the disorder (who tend to fall asleep after 10 to 20 minutes).
Narcolepsy is formally diagnosed when a patient is unable to resist falling asleep on a daily basis for a period of at least three months. The patient must feel refreshed upon awakening and experience either cataplexy, recurrent episodes of REM sleep during the transition between sleep and wakefulness (as evidenced by the presence of <1>hypnagogic hallucinations or sleep paralysis), or both. Although a polysomnogram is not necessary to diagnose narcolepsy, most physicians will recommend one to identify specific symptoms of a patient’s condition and potentially help with treatment.
Treatment options for narcolepsy
Although there is no cure for narcolepsy, the disorder can be treated in a manner that minimizes symptoms and allows patients to live full lives. Stimulant drugs that arouse the central nervous system (CNS) can help patients remain awake during the day. Traditional stimulants may cause side effects such as nervousness and heart palpitations. Some patients may prefer to use a new type of stimulant medication called modafinil that appears to cause fewer side effects. Pregnant women who take medications to control narcolepsy may have to temporarily suspend the use of these drugs because their effect on a developing fetus is unknown.
Antidepressants are often prescribed for patients who experience cataplexy (a sudden loss of muscle tone), hypnagogic hallucinations (intense, frightening dreams that occur when patients are partially awake and are perceived as reality) and sleep paralysis (phenomenon marked by a temporary inability to move). These drugs suppress REM sleep, which helps lessen these symptoms. It is important to note that the U.S. Food and Drug Administration (FDA) has advised that antidepressants may increase the risk of suicidal thinking in some patients and all people being treated with them should be monitored closely for unusual changes in behavior.
In some cases, the drug sodium oxybate may be prescribed to improve the quality of sleep, although it has potential for abuse and its use is tightly controlled.
Patients are urged to remember that medications and lifestyle changes are intended to reduce symptoms and cannot be expected to eliminate them. Support groups and psychotherapy are available to help patients cope with their disorder.
Lifestyle issues for narcolepsy
Patients with narcolepsy are encouraged to talk to employers or teachers about their condition and ways to accommodate their needs. The Americans with Disabilities Act prohibits discrimination against employees with medical conditions such as narcolepsy.
Patients are also encouraged to take caution to help ensure that they remain safe during certain activities. For example, patients should talk to their physician about what they can do to stay alert during long drives and should arrange to take naps or engage in forms of exercise at times when they feel especially drowsy.
In addition, patients can make several lifestyle changes that can help keep narcolepsy better contained. These include going to bed and waking up at the same time every day, taking short naps throughout the day and getting regular exercise, which can help patients stay more alert during the day and sleep better at night. Caffeine, nicotine and alcohol use should be avoided, because these substances can worsen symptoms. Heavy meals should also be avoided.
Questions for your doctor regarding narcolepsy
Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following narcolepsy-related questions:
- What tests will you perform to see if I have narcolepsy?
- What other conditions might be causing my symptoms?
- How will you know if narcolepsy is the source of my symptoms?
- Would I benefit from an overnight visit to a sleep center?
- What are my treatment options?
- Which medication is best for me?
- What lifestyle changes can I make to reduce symptoms?
- How can I best approach my boss/teacher about making necessary changes in my routine?
- What precautions do I need to take to keep myself safe?
- How can I find out about local narcolepsy support groups?