Narcolepsy
(Uncontrollable Sleepiness)
In this condition factsheet:
The Facts on Narcolepsy
Narcolepsy is a sleep disorder that is often under-recognized and underdiagnosed. About 1 in every 2,000 people in North America and Europe suffer from narcolepsy, which tends to be a lifelong phenomenon. The symptoms of narcolepsy can be terrifying at first and frustrating even after someone becomes used to them, but they never produce any serious illness. People with narcolepsy are usually healthy in all other respects. They have exactly the same natural life expectancy as those without it. No physical abnormality or tissue damage has ever been linked to this condition, either as a cause or as a consequence.
Men and women are equally likely to suffer from narcolepsy. Some studies suggest that genetics could play a role in narcolepsy, but the risk of parents passing it on to their children is very low. It usually first appears in the teenage years, but it can come on at almost any age. Often the symptoms appear one by one, but in people aged over 20 it's more likely that several symptoms will appear at once. Symptoms may change over time in an individual, but there's no general tendency for them to get worse or better with age.
Causes of Narcolepsy
It is thought that people with narcolepsy have low levels of a brain protein called hypocretin (also known as orexin). This protein controls wakefulness and without it, people have a hard time staying awake. It is uncertain why some people have low levels of hypocretin, but scientists think this could be a result one or more of the following: genetic mutations of a sleep gene, a family history, infections, brain injuries or tumours, contact with toxic substances (e.g., pesticides), and autoimmune diseases (e.g., rheumatoid arthritis).
One of the phases of sleep is called rapid eye movement (REM) sleep. In a normal sleep cycle, this usually occurs within 80 to 100 minutes of falling asleep. In a person with narcolepsy, REM sleep can occur anytime, even while a person is awake.
The low brain level of hypocretin is likely what causes a person with narcolepsy to enter rapid eye movement (REM) sleep in the daytime. This can be very concerning because a person's muscles in REM sleep are also paralyzed. Therefore, a person with narcolepsy could be standing up awake one moment and falling to the floor asleep the next.
Symptoms and Complications of Narcolepsy
There are a number of common symptoms of narcolepsy, but very few people have all of them.
The first and most important is excessive daytime sleepiness, so extreme that it becomes impossible to stay awake for more than a few moments no matter how hard the person tries, even if they're standing up. This may occur at any time, but is most likely to occur when the person is passive or bored–for example, in the classroom or at work. In a few cases, however, it occurs during physical exertion or stress, or when driving, eating, or speaking.
It's not difficult to rouse someone from such a state, and upon waking people may feel refreshed, but the tiredness may return very soon, forcing another bout of sleep. This may happen several times a day in the most severe cases. If someone with narcolepsy is left undisturbed, the sleep may last from a few minutes to a few hours.
Despite this, people with narcolepsy do not actually tend to sleep more hours in a day than people without the condition. This naturally implies that people with this condition get less sleep at night, and indeed many complain of unrefreshing nighttime sleep that's often interrupted by nightmares.
The other symptoms of narcolepsy (cataplexy, sleep paralysis, and Hypnagogic phenomena) are rarer, but most sufferers experience at least one of them from time to time. They all occur in fully conscious people and can be frightening if the person hasn't yet been diagnosed and doesn't know that they have narcolepsy.
In cataplexy, a person experiences emotionally triggered episodes of muscle weakness, most commonly in the face, neck, and knees. The low muscle tone of REM sleep appears suddenly in a person who is fully awake at a time of strong emotion. Laughter, anger, fear, happiness, stress, or excitement can cause a person to go suddenly limp and drop to the ground.
Sleep paralysis occurs just before going to sleep or just after waking up. A temporary but complete paralysis prevents the person from moving for a few seconds. Sleep paralysis isn't actually that rare, especially in children, but it's only a sign of narcolepsy if the person also experiences the primary symptom of suddenly falling asleep in the daytime.
Hypnagogic phenomena (hallucinations) also occur just before drifting off to sleep. Hypnopompic phenomena are hallucinations that occur just after waking, but are even rarer. Basically, they are vivid dreams that project into the waking period. Because they occur in people who aren't actually asleep, these dreams are sometimes called hallucinations.
As well as briefly falling asleep several times during the day, people with narcolepsy are prone to waking up several times a night. Sleep may be disrupted by insomnia, vivid dreams, sleep apnea and leg movements
There is one potential complication of narcolepsy, which is also a risk in other sleep disorders, and that's having an accident due to fatigue. The urge to sleep is so sudden and irresistible that it's more like passing out than going to sleep. These are sometimes called “sleep attacks”. It's been known to happen while operating a motor vehicle or heavy machinery. Similarly, people who don't sleep well at night may be below par in the daytime, whether they feel an urge to sleep or not. Even minor fatigue can impair judgement, making vehicles and heavy machinery dangerous. Controlling the symptoms of narcolepsy can go a long way towards preventing accidents.
