Narcolepsy is a chronic, neurological disorder that affects the control of sleep and wakefulness. It causes fragmented night sleep and excessive daytime sleepiness.
It also features abnormal rapid eye movement (REM) sleep and it can involve cataplexy, brief attacks of muscle weakness and tone that can lead to body collapse.
Narcolepsy can range in severity from mild to severe. In severe cases, it can negatively impact social activities, school, work, and overall health and well-being. A person with narcolepsy may fall asleep at any time, for example, while talking or driving.
Symptoms tend to appear in the teenage years, or early twenties and thirties. Men and women are equally susceptible, and it is thought to affect 135,000 to 200,000 people in the United States at any one time.
Fast facts on narcolepsy
Here are some key points about narcolepsy. More detail is in the main article.
- Around 1 in 2,000 people in the United States have narcolepsy.
- The main symptoms are excessive daytime sleepiness and abnormal rapid eye movement (REM) sleep.
- Narcolepsy is the second leading cause of excessive daytime sleepiness after obstructive sleep apnea.
- Symptoms typically begin between the ages of 10 and 30 years.
- Narcolepsy can be treated with medications and lifestyle adjustments.
Narcolepsy is a considered a hypersomnia, or a sleep disorder characterized by excessive daytime sleepiness.
In a typical sleep cycle, a person enters the early stage of sleep, followed by deeper sleep stages for 90 minutes where finally REM sleep occurs.
For people with narcolepsy, REM sleep occurs within 15 minutes in the sleep cycle, and intermittently during the waking hours. It is in REM sleep that dreams and muscle paralysis occur.
There are three types of narcolepsy:
- Type 1: Narcolepsy with cataplexy
- Type 2: Narcolepsy without cataplexy, which mainly involves excessive daytime sleepiness
- Secondary narcolepsy: This can result from an injury to the hypothalamus, a part of the brain involved in sleep.
The exact cause is unknown, but narcolepsy may be an inherited autoimmune disease that leads to a deficiency in hypocretin, or orexin, a chemical the brain needs to stay awake. There may be a genetic disposition, which means it runs in families.
Hypocretin is a neurotransmitter, a nerve-signaling chemical. It controls whether we are asleep or awake by acting on different groups of nerve cells, or neurons in the brain. It is made in the hypothalamus region of the brain.
Most people with type 1 narcolepsy have low levels of this hormone, but those with type 2 do not.
Hypocretin is needed to help us stay awake. When it is not available, the brain allows REM sleep phenomena to intrude into normal waking periods. As a result, people with narcolepsy experience both excessive daytime sleepiness and nighttime sleeping problems.
In an autoimmune disorder, the body's immune system mistakenly attacks itself and fights off healthy cells as if they were foreign invaders. Other autoimmune diseases include rheumatoid arthritis, type 1 diabetes, and celiac disease.
A brain injury, tumor, or other disease that affects the brain can sometimes lead to narcolepsy.
The hallmark symptom of narcolepsy is excessive daytime sleepiness (EDS). Additional symptoms may include cataplexy, hypnagogic hallucinations, and sleep paralysis.
Excessive daytime sleepiness (EDS) is a persistent background feeling of sleepiness with a tendency to doze off at intervals throughout the day, often at inappropriate times. These are known as sleep attacks. It can lead to brain fog, poor concentration, decreased energy, memory lapses, exhaustion, and a depressed mood.
Hypnogogic hallucinations are vivid, often frightening sensory hallucinations that occur while falling asleep. These could be caused by the blend of wakefulness and the dreaming that occurs with REM sleep.
Cataplexy is a sudden muscle weakness in the face, neck, and knees. Some people have only mild weakness, such as head or jaw drop, but some people completely collapse to the ground. These episodes are often triggered by strong emotions, such as surprise, laughter, or anger. The weakness is temporary, lasting 2 minutes or less.
Sleep paralysis is a brief inability to move or speak while falling asleep or waking up. These episodes can last from a few seconds to several minutes. After the episode ends, people rapidly recover their full capacity to move and speak.
Automatic behaviors can also occur. A person may fall asleep momentarily but continue doing the previous activity, such as driving, without being conscious.
Chronic daytime sleepiness can stem from a number of conditions. Anyone experiencing excessive sleepiness should seek a medical evaluation to determine the exact cause.
To determine if a person has narcolepsy, a thorough medical and sleep history, physical exam, and sleep studies, such as a polysomnography and multiple sleep latency test, need to be done.
Questions a medical provider may ask on obtaining a sleep history include:
- Are you sleepy most of the day?
- How many hours are you sleeping at night?
- Do you feel rested on waking?
- Are your naps refreshing?
- Do you experience unusual sensations as you are falling asleep?
- Are you ever unable to move as you fall asleep or when you first awake?
- Do you have muscle weakness or collapse when laughing or angry?
Sleep studies can help confirm a diagnosis of narcolepsy. The polysomnography is done with an overnight in a sleep clinic. The multiple sleep latency test is done a few hours after the polysomnography.
Keeping a sleep journal may help with diagnosis.
There is no cure for narcolepsy, but medication can help manage the symptoms. Stimulants can treat sleepiness. Antidepressants can treat symptoms of cataplexy and abnormal REM sleep.
EDS is treated with amphetamine-like stimulants, such as dexamphetamine, methylphenidate, or modafinil. These drugs are first-line therapy because of their low cost, availability, and higher efficacy.
However, they are controlled substances. Except for Modafinil, they can lead to tolerance and abuse.
Cataplexy can be lessened by antidepressant drugs, which suppress REM sleep.
Clomipramine is used to treat narcolepsy. Selective serotonin reuptake inhibitors (SSRIs) and selective norepinephrine reuptake inhibitors (SNRIs) may also be effective. Side effects may include dry mouth, constipation, and blurred vision.
Sodium oxybate can relieve EDS, poor nighttime sleep, and cataplexy. It has few side effects and very little interaction with other drugs.
The individual must avoid any activity that could pose a health threat, such as using machinery or driving, until any cataplexy is controlled.
Treatment may need adjusting as symptoms change.
Lifestyle modifications can help. These include attention to sleep hygiene, scheduling daytime naps, and establishing a normal exercise and meal schedule.
Here are some guidelines for good sleep hygiene:
- Keep a consistent sleep schedule, getting up and going to bed at the same time every day, even on weekends or during vacations.
- Set a bedtime that will allow at least 7 hours of sleep.
- Do not go to bed unless you are sleepy.
- If you do not fall asleep after 20 minutes, get out of bed.
- Establish relaxing bedtime rituals.
- Use your bed only for sleep and sex.
- Make your bedroom quiet and relaxing, with a comfortable, cool temperature.
- Limit exposure to light in the evenings.
- Avoid large meals before bedtime. If you are hungry at night, eat a light, healthy snack.
- Reduce fluid intake before bedtime.
- Exercise regularly and maintain a healthy diet.
- Avoid consuming caffeine in the late afternoon or evening.
- Avoid alcohol.
Medical News Today asked Monica Gow, cofounder and board member of Wake Up Narcolepsy (WUN), about the main challenges facing people with the condition.
She told us:
"People with narcolepsy face many challenges, but the main ones are accurate diagnosis in a timely manner, finding a physician who can effectively manage the narcolepsy and finding the right combination of treatment to allow for daily functioning at the highest possible level considering the medical disorder at hand."
WUN is a nonprofit organization that people with narcolepsy by funding research and increasing awareness.
Ms. Gow also advised us that: "Friends and family can be empathetic to loved ones with narcolepsy and educate themselves on narcolepsy and all that is involved with it."
There is no cure for narcolepsy, but prescription medication and good lifestyle habits can help manage the condition.
According to the National Institute of Neurological Disorders and Stroke (NINDS), symptoms often become more severe over the 20 to 30 years after they first appear, but daytime sleepiness may reduce after the age of 60 years.
Organizations such as WUN can help people keep up-to-date with the latest developments. They also invite people to join in the search for a cure by participating in research projects.