Narcolepsy, also known as hypnolepsy, is a chronic brain disorder that involves poor control of sleep-wake cycles. People with narcolepsy experience excessive daytime sleepiness and intermittent, uncontrollable episodes of falling asleep during the daytime. These sudden sleep attacks may occur during any type of activity at anytime of the day. Narcolepsy can greatly affect daily activities. People may unwillingly fall asleep while at work or at school, when having a conversation, playing a game, eating a meal, or, most dangerously, when driving or operating other types of machinery.
Many cases of narcolepsy are caused by a lack of the brain chemical orexin, also known as hypocretin, which regulates sleep.
This deficiency is thought to result from the immune system mistakenly attacking parts of the brain that produce this chemical.
However, this does not explain all cases of narcolepsy, and the exact cause of this problem is often unclear.
Factors that have been suggested to trigger narcolepsy include hormonal changes, which can occur during puberty or the menopause, major psychological stress, a sudden change in sleep patterns and an infection such as flu.
The symptoms of narcolepsy most commonly begin between the ages of 10 and 25. They may worsen for the first few years, and then continue for life. They include:
- Excessive daytime sleepiness. People with narcolepsy fall asleep without warning, anywhere, anytime. For example, you may suddenly nod off while working or talking with friends. You may sleep for a few minutes or up to a half-hour before awakening and feeling refreshed, but eventually you fall asleep again. You also may experience decreased alertness throughout the day. Excessive daytime sleepiness usually is the first symptom to appear and is often the most troublesome, making it difficult for you to concentrate and fully function.
- Sudden loss of muscle tone. This condition, called cataplexy (KAT-uh-plek-see), can cause a number of physical changes, from slurred speech to complete weakness of most muscles, and may last for a few seconds to a few minutes. Cataplexy is uncontrollable and is triggered by intense emotions, usually positive ones such as laughter or excitement, but sometimes fear, surprise or anger. For example, your head may droop uncontrollably or your knees may suddenly buckle when you laugh. Some people with narcolepsy experience only one or two episodes of cataplexy a year, while others have numerous episodes daily. Not everyone with narcolepsy experiences cataplexy.
- Sleep paralysis. People with narcolepsy often experience a temporary inability to move or speak while falling asleep or upon waking. These episodes are usually brief lasting one or two minutes but can be frightening. You may be aware of the condition and have no difficulty recalling it afterward, even if you had no control over what was happening to you. This sleep paralysis mimics the type of temporary paralysis that normally occurs during rapid eye movement (REM) sleep, the period of sleep during which most dreaming occurs. This temporary immobility during REM sleep may prevent your body from acting out dream activity. Not everyone with sleep paralysis has narcolepsy, however. Many people without narcolepsy experience some episodes of sleep paralysis, especially in young adulthood.
- Hallucinations. These hallucinations are called hypnagogic hallucinations if occurring as you fall asleep and hypnopompic hallucinations if occurring upon waking. Because you may be semi-awake when you begin dreaming, you experience your dreams as reality, and they may be particularly vivid and frightening.
People with narcolepsy may have other sleep disorders, such as obstructive sleep apnea, a condition in which breathing starts and stops throughout the night, restless legs syndrome and even insomnia. People with narcolepsy may also act out their dreams at night by flailing their arms or kicking and screaming.
Some episodes of sleep attacks are brief, lasting seconds. Some people with narcolepsy experience automatic behavior during these brief episodes. For example, you may fall asleep while performing a task you normally perform, such as writing, typing or driving, and you continue to function while asleep. When you awaken, you can’t remember what you did, and you probably didn’t do it well.
A physical exam and exhaustive medical history are essential for proper diagnosis of narcolepsy. However, none of the major symptoms is exclusive to narcolepsy. Several specialized tests, which can be performed in a sleep disorders clinic or sleep lab, usually are required before a diagnosis can be established. Two tests that are considered essential in confirming a diagnosis of narcolepsy are the polysomnogram (PSG) and the multiple sleep latency test (MSLT). The PSG is an overnight test that takes continuous multiple measurements while a patient is asleep to document abnormalities in the sleep cycle. A PSG can help reveal whether REM sleep occurs at abnormal times in the sleep cycle and can eliminate the possibility that an individual’s symptoms result from another condition.
The MSLT is performed during the day to measure a person’s tendency to fall asleep and to determine whether isolated elements of REM sleep intrude at inappropriate times during the waking hours. As part of the test, an individual is asked to take four or five short naps usually scheduled two hours apart.
There is currently no cure for narcolepsy, but making changes to improve your sleeping habits and taking medication can help minimise the impact the condition has on your daily life.
Taking frequent, brief naps evenly spaced throughout the day is one of the best ways to manage excessive daytime drowsiness. This may be difficult when you are at work or school, but your GP or specialist may be able to devise a sleep schedule that will help you get into a routine of taking naps.
Keeping to a strict bedtime routine can also help, so you should go to bed at the same time each night whenever possible.
If your symptoms are particularly troublesome, you may be prescribed medication that can help reduce daytime sleepiness, prevent cataplexy attacks and improve your sleep at night. These medications are usually taken as daily tablets, capsules or drinkable solutions.
What behavioral strategies help people cope with symptoms?
Currently available medications do not enable all people with narcolepsy to consistently maintain a fully normal state of alertness. Drug therapy should accompany various behavioral strategies according to the needs of the affected individual.
Many individuals take short, regularly scheduled naps at times when they tend to feel sleepiest.
Improving the quality of nighttime sleep can combat EDS and help relieve persistent feelings of fatigue. Among the most important common-sense measures people can take to enhance sleep quality are:
- maintain a regular sleep schedule – go to bed and wake up at the same time every day
- avoid alcohol and caffeine – containing beverages for several hours before bedtime
- avoid large, heavy meals just before bedtime
- avoid smoking, especially at night
- maintain a comfortable, adequately warmed bedroom environment, and
- engage in relaxing activities such as a warm bath before bedtime
Exercising for at least 20 minutes per day at least 4 or 5 hours before bedtime also improves sleep quality and can help people with narcolepsy avoid gaining excess weight.
Safety precautions, particularly when driving, are particularly important for all persons with narcolepsy. EDS and cataplexy can lead to serious injury or death if left uncontrolled. Suddenly falling asleep or losing muscle control can transform actions that are ordinarily safe, such as walking down a long flight of stairs, into hazards. People with untreated narcoleptic symptoms are involved in automobile accidents roughly 10 times more frequently than the general population. However, accident rates are normal among individuals who have received appropriate medication.
Support groups frequently prove extremely beneficial because people with narcolepsy may become socially isolated due to embarrassment about or misunderstandings related to their symptoms. Many people also try to avoid strong emotions, since humor, excitement, and other intense feelings can trigger cataplectic attacks. Support groups also provide individuals with a network of social contacts who can offer practical help and emotional support.