What is narcolepsy?
Narcolepsy is a chronic neurological disorder of excessive daytime sleepiness. It may occur with other symptoms such as cataplexy, sleep paralysis and hallucinations.
All people with narcolepsy have excessive drowsiness. You may have a lack of energy. Strong urges to nap can happen at any time of the day. Naps might last for minutes or up to an hour or more. After a nap you may be alert for several hours. While this may happen every day it is not because you aren’t sleeping enough at night. Sometimes these develop years after the sleepiness, and sometimes they don’t occur at all.
Cataplexy is a sudden loss of muscle function while conscious. You may have a total collapse or just weakness in the knees or face muscles. It may last from a few seconds to a few minutes. Cataplexy is triggered by sudden emotions such as laughter, anger or fear.
Occasionally you may wake up momentarily unable to move any part of your body. This is called sleep paralysis. Usually it lasts between a few seconds and a few minutes. You may feel frightened by it, although it will not cause you harm. Sleep paralysis also happens in people without narcolepsy. While narcolepsy is uncommon (see below) isolated episodes of sleep paralysis can occur in about 15% of the population.
Some people with narcolepsy also report hallucinations. You may see or hear things that are not really there, especially if you are drowsy.
What causes narcolepsy?
The part of the brain which controls falling asleep functions abnormally. During the day when normally awake and active, you might fall asleep with little warning, rapidly going into a stage of sleep called Rapid Eye Movement (or REM) sleep. During normal REM sleep there is both dreaming and temporary loss of muscle tone. In narcolepsy normal REM sleep may become disrupted and there might be hallucinations, cataplexy and sleep paralysis. It is thought that narcolepsy is related to lack of a brain chemical called hypocretin. In some cases (but not all) it is an inherited condition.
How common is narcolepsy?
It affects about 1 person in 2000. Both men and women get narcolepsy. It can occur at any age but is usually first noted between the ages of 10 and 30.
How does it affect people?
Onset may be gradual or sudden. You may notice the irresistible sleepiness first and other symptoms only appear many years later. Working and learning is likely to be difficult because of sleepiness. Others often mistake your sleepiness for lack of interest or motivation. You may also feel depressed. You should only drive a car if your symptoms are well controlled with medication.
Where and when should you seek help?
If you have been struggling with unexplained sleepiness you should talk to your doctor (see Excessive Daytime Sleepiness). Any symptoms that could be cataplexy should not be ignored. You are not likely to have narcolepsy if you feel tired and/or fatigued without the urge to sleep across the day.
What might your doctor do?
If your GP feels you may have a sleep disorder they will refer you to a sleep specialist. Many patients have had narcolepsy for many years before it is diagnosed. To be diagnosed with narcolepsy you are likely to need a “Multiple Sleep Latency Test” in a clinic that conducts sleep studies.
What is the Multiple Sleep Latency Test?
After doing a night-time sleep study you will be asked to try to nap every two hours throughout the day while your sleep is measured. You will be given a 20 minute opportunity to fall asleep at times at two-hourly intervals – often at times such as 9am, 11am, 1pm and 3pm. There are two things being measured. One is how long it takes you to fall asleep. The other is whether you go straight into REM sleep when you fall asleep. (See Facts about Sleep to read about REM sleep). Falling asleep quickly and going quickly into REM sleep are likely to indicate narcolepsy.
What else might cause the symptoms?
There are many possible reasons why you may be feeling sleepy or tired. Think about all the possible options (see Excessive Daytime Sleepiness). If you have eliminated all other possible reasons and you do not meet the criteria for narcolepsy you may be diagnosed with idiopathic hypersomnia.
What is idiopathic hypersomnia?
Unlike people with narcolepsy, people with this condition do not fall rapidly into REM sleep following the onset of sleep and do not have other symptoms like cataplexy. There are a number of potential causes of idiopathic hypersomnia but the condition is not well understood. See Idiopathic Hypersomnia.
How is narcolepsy treated?
There is no cure for narcolepsy but some of the symptoms may be controlled with medication. Stimulants are prescribed to help with sleepiness. Anti-depressant medications may be used to control cataplexy. You will feel more alert if you can build in power naps across the day.
What could you do to help with symptoms?
You need to adapt your lifestyle. Avoid situations where sleepiness is dangerous, such as driving. Planned daytime naps will help control the urge to sleep. Keep regular night sleep hours. Cataplexy may be reduced by learning to flatten your emotional responses.Ensure family and friends understand how the condition affects you.
Where can I find out more?
Asutralian support group for narcolepsy: http://www.narcolepsysupportaustralia.com/
Australian self- help group for narcolepsy: http://www.nodss.org.au/
US self-help group for narcolepsy: http://narcolepsynetwork.org/
Dirving and narcolepsy: http://healthysleep.med.harvard.edu/narcolepsy/living-with-narcolepsy/safety