Narcolepsy is an under-diagnosed, disabling disorder of the brain that affects the control of sleep and wakefulness.
Individuals with narcolepsy experience chronic daytime sleepiness, abnormal rapid eye movement sleep, and cataplexy (brief attacks of muscle weakness and tone triggered by strong emotions).
Narcolepsy can range in severity from mild to severe, and negatively impact one's social activities, school, work, and overall health and well-being.
Narcolepsy typically begins in the teen years, or early twenties and thirties. It affects 3 million people worldwide. The exact cause of narcolepsy is unknown, although researchers believe it to be an inherited autoimmune disease that leads to a deficiency in hypocretin, a chemical the brain needs to stay awake.
Although there is no cure for narcolepsy, it can be managed with lifestyle modifications and medication therapy.
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Here are some key points about narcolepsy. More detail and supporting information is in the main article.
- 40 million Americans each year suffer from chronic, long-term sleep disorders.
- Although highly prevalent, common sleep disorders are infrequently identified by primary care providers.
- Narcolepsy is the second leading cause of excessive daytime sleepiness after obstructive sleep apnea.
- The average time from the onset of narcolepsy to diagnosis is about 10 years.
- Symptoms typically begin to occur between the ages of 10 and 30.
- Narcolepsy is caused by the loss of the two brain chemicals called hypocretins.
- Researchers have identified a gene that is linked to narcolepsy.
- The main symptoms of narcolepsy are excessive daytime sleepiness and abnormal rapid eye movement (REM) sleep.
- The medical community first recognized narcolepsy in the late 19th century.
- Approximately 1:2000 people have the disorder.
- It is equally common in men and women.
- Narcolepsy can be treated with medications and adjustments to lifestyle.
What is narcolepsy?
Narcolepsy is a considered a hypersomnia or a sleep disorder characterized by excessive daytime sleepiness.
Many cases of narcolepsy are caused by a lack of the brain chemical orexin (also known as hypocretin), which regulates sleep.
In a typical sleep cycle, we enter 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 almost immediately in the sleep cycle, and intermittently during the waking hours. It is in REM sleep that dreams and muscle paralysis occur.
Causes of narcolepsy
Nerve-signaling chemicals called neurotransmitters control whether we are asleep or awake by acting on different groups of nerve cells, or neurons in the brain.
Narcolepsy results from the loss of the neurotransmitters known as hypocretin (also called orexin). These neurotransmitters are made in the hypothalamus region of the brain and are necessary to maintain wakefulness.
When hypocretin is not available, the brain allows REM sleep phenomena to intrude into normal waking periods. As a result, people with narcolepsy suffer from excessive daytime sleepiness, and nighttime sleeping problems.
Narcolepsy is believed to be an autoimmune disease with a genetic predisposition. An autoimmune disease is a disorder where the body's immune system mistakenly attacks itself and fights off healthy cells as if they were foreign invaders. Some commonly recognized autoimmune diseases are rheumatoid arthritis, type 1 diabetes, and celiac disease.
Symptoms of narcolepsy
The hallmark symptom of narcolepsy is excessive daytime sleepiness (EDS). Additional symptoms may include cataplexy, hypnagogic hallucinations, and sleep paralysis.
In most cases, excessive daytime sleepiness is the first sign of narcolepsy. This can have a significant impact on everyday life.
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 (sleep attacks).
EDS can lead to brain fog, poor concentration, decreased energy, memory lapses, exhaustion, and a depressed mood.
Cataplexy is a sudden muscle weakness in the face, neck, and knees. Some people have only mild weakness such as head or jaw drop, while others will completely collapse to the ground. These episodes are generally triggered by strong emotions like surprise, laughter, or anger. The weakness is temporary, lasting two minutes or less.
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.
Sleep paralysis is a brief inability to move or speak while falling asleep or waking up. These episodes typically last a few seconds to several minutes. After the episode's end, people rapidly recover their full capacity to move and speak.
Tests and diagnosis of narcolepsy
All individuals with chronic daytime sleepiness require a medical evaluation to determine the exact cause. Feeling tired all the time is a common complaint, with many underlying causes.
To determine if it is narcolepsy, a thorough medical and sleep history, physical exam, and sleep studies (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 are helpful to confirm the 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.
Treatments for narcolepsy
Although there is no cure for narcolepsy, the symptoms can be managed with medications. Sleepiness is treated with stimulants, while the symptoms of cataplexy and abnormal REM-sleep can be treated with antidepressants.
There are steps you can take to reduce excessive daytime sleepiness such as sticking to a strict bedtime routine - aim to go to bed and wake up at the same time every day when possible.
The EDS is treated with amphetamine-like stimulants like dexamphetamine, methylphenidate or modafinil. These drugs are first-line therapy because of their low cost, availability, and higher efficacy.
These medications are controlled substances, and with the exception of Modafinil, tolerance and abuse is possible.
Cataplexy can be lessened by antidepressant drugs, which work by suppressing REM sleep. Clomipramine is indicated for use in narcolepsy. Additionally, SSRIs and SNRIs have shown to be effective. Side effects may include dry mouth, constipation, and blurred vision.
For individuals who have EDS, poor nighttime sleep, and cataplexy, sodium oxybate is an efficacious drug for all three symptoms. It has minimal side effects and very little interaction with other drugs.
In addition to medication, lifestyle adjustments such as attention to sleep hygiene, scheduling daytime naps, and establishing a normal exercise and meal schedule may also help to reduce narcolepsy symptoms. It is also imperative to avoid any activity that could pose a health threat until any cataplexy is controlled.
Here are some guidelines for good sleep hygiene:
- Keep a consistent sleep schedule. Get up and go to bed at the same time every day, even on weekends or during vacations
- Set a bedtime that is early enough for you to get 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. Keep the room at a comfortable, cool temperature
- Limit exposure to light in the evenings
- Do not eat a large meal before bedtime. If you are hungry at night, eat a light, healthy snack
- Reduce your fluid intake before bedtime
- Exercise regularly and maintain a healthy diet
- Avoid consuming caffeine in the late afternoon or evening
- Avoid alcohol.
Narcolepsy is a chronic neurological disorder that causes fragmented night sleep, excessive daytime sleepiness, and sudden body collapses from temporary muscle weakness. It typically begins in the teens or early twenties.
As drowsiness or feeling tired all the time is a common, universal complaint, it can take many years to determine the cause is narcolepsy.
All individuals with chronic daytime sleepiness should see their primary care provider to determine the underlying cause.
Although there is no cure for narcolepsy, with prescription medication and good lifestyle habits, individuals with narcolepsy can live healthy, normal lives.
Around 3 million people worldwide suffer from narcolepsy or bouts of sleepiness and sleep attacks that can affect their ability to have a normal life. There is no cure for the disorder, and few clues about its causes. But now, a new study suggests it could be an autoimmune disease.
Narcolepsy - extreme bouts of sleepiness that can strike at any time - affects around 1 in 2,000 people in the US. A new study raises concerns about its diagnosis in adolescents, after it identified marijuana in the urine of some teenagers who had symptoms consistent with narcolepsy.