An extreme tendency to fall asleep during normal waking hours
- Usually develops between the ages of 15 and 30
- Sometimes runs in families
- Gender and lifestyle are not significant factors
People with narcolepsy fall asleep at any time of the day, often when carrying out a monotonous task. Sleep may also occur at inappropriate times, such as while eating. Affected people can be awakened easily but may fall asleep again soon afterwards. Narcolepsy can seriously interfere with daily life.
Some people with narcolepsy have vivid hallucinations just before falling asleep. Others find that they are unable to move while they are falling asleep or waking up (sleep paralysis). About 3 in 4 people with narcolepsy also have cataplexy, in which there is a temporary loss of strength in the limbs that causes the person to fall to the ground. Cataplexy is sometimes triggered by an emotional response, such as fear or laughter.
Narcolepsy is due to low levels of the hormone hypocretin (also called orexin) in the brain. This hormone is produced by cells in the hypothalamus and helps to regulate wakefulness and sleep. In people with narcolepsy, the cells that produce hypocretin are damaged, although it is not known why this damage occurs. Narcolepsy is thought to affect about 3–5 people in 10,000 in the UK. It usually first appears between the ages of 15 and 30, although its onset sometimes occurs during childhood or middle age.
What might be done?
Your doctor will probably diagnose narcolepsy from your symptoms. EEG may also be used to record the electrical activity of your brain. These tests may be carried out while you are asleep in a hospital clinic.
You should take regular, short naps during the day and keep busy while you are awake. Your doctor may prescribe stimulant drugs to help you to keep awake. Certain tricyclic antidepressant drugs are useful in treating people with cataplexy.
Although narcolepsy is usually a lifelong condition, in some cases, there is a spontaneous improvement over time.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.
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