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Narcolepsy

Published by Bupa's health information team, June 2009.

This factsheet is for people who have narcolepsy, or who like more information about it.

Narcolepsy is a type of sleep disorder that causes you to feel irresistibly sleepy or to fall asleep during the day.

Some people with narcolepsy also have cataplexy, in which you suddenly lose strength in your muscles. This is brought on by emotion, for example laughing.

• About narcolepsy
• Symptoms of narcolepsy
• Causes of narcolepsy
• Diagnosis of narcolepsy
• Treatment of narcolepsy
• Living with narcolepsy
• Questions and answers
• Further information
• Sources

About narcolepsy

Narcolepsy causes you to have attacks of irresistible sleepiness. People who have narcolepsy will find themselves very feeling sleepy in the daytime, and may fall asleep at inappropriate times, for example at meal times.

Between one half and two-thirds of all people with narcolepsy also have cataplexy. This is when your muscles suddenly become weak. Narcolepsy with cataplexy affects between three and five in every 10,000 people in Europe.

Narcolepsy usually starts when you are a teenager, but it often takes up to a decade or more before it is properly diagnosed. Narcolepsy can cause problems in social situations, when it cause embarrassment, and it may also affect academic and job performance.

Symptoms of narcolepsy

Narcolepsy has several different symptoms. The main symptoms of narcolepsy are listed below.

• Excessive daytime sleepiness. This is more than just feeling tired because of a poor night's sleep. People with narcolepsy often have a persistent feeling of mild sleepiness, punctuated by attacks of an irresistible urge to sleep. These attacks are particularly common while you are doing a boring or repetitive task. They can happen at inappropriate times such as at meal times, or even while driving. You may have several sleep attacks a day. Naps tend to last from a few minutes to an hour.
• Cataplexy. This is a sudden loss of strength in your muscles, triggered by strong emotions such as laughter, anger or elation. It can happen to different groups of muscles, but may affect just one side of the body. How severe it is varies between people; in some, just facial muscles may weaken, others may completely collapse because of leg weakness. The attacks are short, lasting from a few seconds up to a couple of minutes. You remain conscious and aware throughout an attack of cataplexy.

As well as the main symptoms of sleepiness and cataplexy, there are a number of other symptoms that you may experience.

• Sleep paralysis. This means waking up in the middle of the night with a feeling of not being able to move for a couple of minutes. It can occasionally occur while going to sleep.
• Hypnagogic hallucinations. These are vivid dream-like hallucinations while falling asleep. You may also have them while waking up (hypnopompic hallucinations).
• Disturbed sleep at night. For example, sleep walking.
• Making mistakes while doing repetitive tasks while feeling sleepy.

Complications of narcolepsy

Narcolepsy can have a significant impact on your life. Education, employment, relationships, driving, mood and relationships can all be affected by it. People may not always understand or accept that attacks of sleepiness are outside of a person's control. Some studies show that it can have as much of an affect your quality of life as other serious illnesses such as Parkinsons's disease.

If you have narcolepsy, it can help to be in contact with other people who have it.

Causes of narcolepsy

Narcolepsy is likely to be inherited. If you have a close relative who has narcolepsy, your risk of having it is estimated to be between 10 to 40 times higher than the general population.

Narcolepsy is thought to be caused by a problem with how your body regulates REM (rapid eye movement) sleep. Many of the symptoms of narcolepsy and cataplexy are aspects of REM sleep that occur while you are awake. This is because REM sleep is the time during which you dream. Muscles normally become paralysed to prevent us acting out these dreams. In sleep paralysis, you partially wake during REM sleep.

It is only recently that doctors have begun to understand what causes narcolepsy. Towards the end of the 1990s, a neurotransmitter called orexin (or hypocretin) that appeared to regulate sleep and how awake you feel was discovered. Researchers found that spinal fluid levels of the orexin are much lower in people who have narcolepsy and cataplexy. However, orexin levels in people with only narcolepsy seem to be normal. Some speculate that narcolepsy may also be caused by a mutation in genes that code for orexin receptors in the brain.

Researchers have also known since the 1980s that people who have narcolepsy and cataplexy have a gene coding for a particular tissue type - HLA DQB1*0602. Tissue type is a term that describes how your tissue is compatible with your immune system. It isn't clear how HLA tissue type relates to narcolepsy but 95% of people with narcolepsy/cataplexy and 40% of people with narcolepsy alone are HLA DQB1*0602. In comparison, only 18 to 35% of the general population are HLA DQB1*0602.

Diagnosis of narcolepsy

It can take several years before someone who has narcolepsy to get a firm diagnosis. This may be because people wait before seeing their doctor, or that the condition goes unrecognised when they do.

If you think you have narcolepsy, you should go and talk to your GP, who will ask you about your symptoms and how long they have lasted. Having cataplexy and daytime sleepiness strongly suggests that you have narcolepsy. If he or she thinks you might have narcolepsy, you might be sent to a sleep clinic.

Sleep clinics specialise in diagnosing sleep disorders. If you are suspected of having narcolepsy, other conditions that cause daytime sleepiness, such as obstructive sleep apnoea, need to be ruled out.

You will probably be asked to stay overnight so that your brain waves and breathing can be monitored while you sleep. If you have narcolepsy you tend to be able to fall asleep very quickly. If you pass quickly or immediately into the REM phase of sleep this is also considered a sign that you have narcolepsy.

You may have a blood sample to check your tissue type and in some clinics a sample of cerebral spinal fluid may also be taken so that orexin levels can be checked.

Treatment of narcolepsy

Narcolepsy is a lifelong condition. However, with the right information and treatment it can be effectively managed.

Non-medical treatment

Sleeping regularly

Sticking to a regular sleep routine may help to limit excessive daytime sleepiness. There is some evidence that having a planned nap in the day may help you perform better in the day without feeling as sleepy.

Diet

Some doctors think that avoiding sugary foods or drinks may reduce sleepiness. Avoiding heavy meals and alcohol may also help.

Exercise

Keeping up regular exercise is thought to help with sleep patterns.

Medicines

Medicines can be used to help treat some of the symptoms of narcolepsy.

Amphetamines

For years, amphetamine-like stimulants such as dexamphetamine sulphate, methamphetamine and methylphenidate have been used for preventing daytime sleepiness. They work by stimulating the central nervous system. Methylphenidate is most commonly used. However these drugs have side-effects such as headache, feeling irritable or nervous, and stomach upset. They can also disturb sleep at night.

Modafinil

This recently developed drug acts in a different way to amphetamines. It is known as a 'wakefulness promoter'. Modafinil doesn't seem to keep you awake at night, although it can cause headaches as a side effect. It hasn't been approved for children to use.

Sodium oxybate

As well as treating excessive daytime sleepiness, sodium oxybate also helps control cataplexy. It is doesn't act as a stimulant like amphetamines or as a wakefulness promoter like modafinil. It may work by allowing you to sleep better at night. As this is a very expensive drug, it is only used for patients not responding to amphetamines or modafinil.

Anti-depressants

Selective serotonin re-uptake inhibitors or tri-cyclic antidepressants can be used to reduce cataplexy.

Living with narcolepsy

You should inform your employer or the school of an affected child and make sure they are given enough information to understand the condition.

Contacting others who are affected by narcolepsy can help. Counselling and moral support offered by organisations such as the Narcolepsy association can be invaluable in learning to live with narcolepsy.

Further information

• Narcolepsy Association UK
  0845 450 0394
  www.narcolepsy.org.uk

Sources

• Kasper DL, Fauci AS, Longo DL, et al. Harrison's Principles of Internal Medicine. 16th ed: McGraw-Hill, 2005:159
• Kumar P, Clark M. Clinical Medicine. 6th ed. London: Elsevier Saunders, 2005:1227
• Zeman A, Britton T, Douglas N, et al. Narcolepsy and excessive daytime sleepiness. BMJ 2004; 329(7468):724-728. www.bmj.com
• Narcolepsy. eMedicine. www.emedicine.com, accessed 21 November 2008
• Narcolepsy Syndrome. Narcolepsy Association UK. www.narcolepsy.org.uk, accessed 10 December 2008
• Insomnia. Clinical knowledge summaries. http://cks.library.nhs.uk, accessed 21 January 2009
• Sleeping Well. The Royal College of Psychiatrists. www.rcpsych.ac.uk, accessed 21 January 2009

This information was published by Bupa's health information team and is based on reputable sources of medical evidence. It has been peer reviewed by Bupa doctors. The content is intended for general information only and does not replace the need for personal advice from a qualified health professional.

Publication date: June 2009