What is Narcolepsy?
Narcolepsy is a lifelong nervous system disorder that affects the control of sleep and wakefulness. It is a rare condition estimated to affect about 1 out of every 2,000 people. People with narcolepsy experience excessive uncontrollable episodes of falling asleep during the daytime.
Narcolepsy causes significant daytime drowsiness and sleep attacks. In a majority of cases, it also causes unexpected and temporary loss of muscle control, known as cataplexy. Narcolepsy isn’t a deadly disease by itself, but episodes can lead to accidents, injuries, or life-threatening situations.
There are two types of narcolepsy:
- Type 1 is narcolepsy with cataplexy, and
- Type 2 is narcolepsy without cataplexy.
Type 1 is the most common. Cataplexy, especially in children, can be mistaken for seizure activity.
Symptoms of Narcolepsy
Sleep experts attribute symptoms of narcolepsy to poorly regulated rapid eye movement (REM) sleep. How often and how intensely symptoms occur can vary. Common symptoms can include:
Cataplexy: This is the sudden, temporary loss of muscle tone. It can be triggered by intense emotions. These may include excitement, laughter, anger, and fear. The frequency of cataplexy varies. Some people may have it several times per day. Other people may experience it a few times per year.
Hallucinations when falling asleep: Hallucinations can also occur in people with narcolepsy. This is because dreaming is typically part of REM sleep. If dreams occur when you’re partially awake, they may seem like reality.
Significant daytime sleepiness: Excessive daytime drowsiness is often the first symptom of narcolepsy. It makes it difficult to function properly during the day.
Sleep paralysis: This is an inability to move or speak while falling asleep, sleeping, or waking. Episodes last only a few minutes. Sleep paralysis mimics the paralysis seen during REM sleep. It does not affect eye movements or the ability to breathe. It can even occur in people who don’t have narcolepsy.
Narcolepsy also can be associated with other sleep disorders, such as obstructive sleep apnea, restless legs syndrome, and insomnia.
Causes of Narcolepsy
The exact cause of narcolepsy is unknown. However, most people with narcolepsy and cataplexy have a decreased amount of a brain protein called hypocretin. One of the functions of hypocretin is regulating your sleep-wake cycles.
Scientists think low hypocretin levels may be caused by several factors. A gene mutation has been identified that causes low levels of hypocretin. It’s believed that this hereditary deficiency, along with an immune system that attacks healthy cells, contributes to narcolepsy. Other factors such as stress, exposure to toxins, and infection also may play a role.
Occurrence of abnormal sleep patterns
Normal sleep occurs in five stages and in cycles. As the sleep cycle begins, we move from light sleep to deep sleep, then into REM sleep, when dreaming and muscle paralysis occur. It takes about 70 to 90 minutes to reach the first cycle of REM sleep. The longer we stay asleep, the more time we spend in REM, and the less time we spend in deep sleep. Scientists believe adequate REM sleep is necessary for our survival.
People with narcolepsy can suddenly fall asleep, lose muscle tone, and begin to dream. This may happen no matter what they’re doing or what time of day it is. When this happens, their REM sleep occurs inappropriately and spontaneously. The symptoms of REM sleep can happen all at once.
Diagnosis of Narcolepsy
The Center for Narcolepsy at the Stanford University School of Medicine reports that one in every 2,000 Americans has narcolepsy. If you have excessive daytime sleepiness or one of the other common symptoms of narcolepsy, talk to your doctor. Daytime sleepiness is common in many types of sleep disorders. Your doctor will ask you about your medical history and perform a physical exam. They’ll look for a history of excessive daytime drowsiness and episodes of sudden loss of muscle tone. The doctor will usually require a sleep study and several other tests to determine the correct diagnosis.
Some common sleep evaluations include the following:
The Epworth Sleepiness Scale (ESS) is a simple questionnaire. It asks how likely you are to sleep in different circumstances.
ActiGraph, or other home monitoring systems, can keep track of how and when you fall asleep. This device is worn like a wristwatch and may be used together with a sleep diary.
Polysomnogram (PSG) testing requires that you spend the night in a medical facility. You’ll be monitored while you sleep with electrodes attached to your scalp to measure brain activity, heart rate and rhythm, eye movement, muscle movement, and breathing. This test can also detect sleep apnea.
A multiple sleep latency test (MSLT) determines how long it takes you to fall asleep during the day. It also looks at how quickly you enter REM sleep. This test is often given the day after a polysomnogram. You’ll need to take four to five naps throughout the day, each two hours apart.
A spinal tap, or lumbar puncture, is used to collect cerebrospinal fluid (CSF) to measure hypocretin levels. Hypocretin in CSF is expected to be low in people with narcolepsy. For this test, your doctor will insert a thin needle between two lumbar vertebrae.
Treatment for Narcolepsy
Narcolepsy has no cure. It’s a chronic condition that lasts a lifetime. The goal of treatment, then, is to control symptoms and improve daytime functioning. Stimulants, lifestyle adjustments, and avoiding hazardous activities are all important in treating this disorder.
There are several classes of medications used to treat narcolepsy. For example:
- Stimulants such as armodafinil (Nuvigil), modifinil (Provigil) and methylphenidate (Ritalin) may be used to improve wakefulness.
- Tricyclic antidepressants can reduce cataplexy, sleep paralysis, and hallucinations. These medications can have unpleasant side effects, such as constipation, dry mouth, and urinary retention.
- Serotonin-norepinephrine reuptake inhibitors (SNRIs), such as venlafaxine (Effexor), can help regulate sleep and mood. They can be useful in treating cataplexy, hallucinations, and sleep paralysis.
- Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine (Prozac), can also help regulate sleep and improve your mood.
Management of Narcolepsy
Here are some steps you can take to make living with narcolepsy easier and safer:
- Tell teachers and supervisors about your condition. If you do fall asleep, they should understand why.
- Be aware that some narcolepsy treatments will cause you to test positive for stimulants on drug screens. Talk to your employer in advance to prevent misunderstandings.
- Eat light or vegetarian meals during the day. Don’t eat a heavy meal before important activities.
- Try taking 10 to 15 minute naps after meals.
- Schedule naps throughout the day. This may help you avoid daytime drowsiness.
- Avoid nicotine and alcohol. They can make symptoms worse
- Exercise regularly. This can help you rest better at night and keep you alert during the day.
- Maintain a healthy weight. Researchers have found an association between narcolepsy and being overweight.
Some states may limit driving privileges for people with narcolepsy. Be sure to check with your local department of motor vehicles. They can help keep you from endangering anyone or breaking the law.