What causes narcolepsy?

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Destruction of brain cells causes narcolepsy

It is now generally believed that, in most cases at least, narcolepsy is an auto-immune disorder, caused by the destruction of certain cells within the brain by the body's own immune system. Those cells are responsible for the production of a peptide molecule called hypocretin (sometimes also called orexin). The cells that produce hypocretin are found in an area of the brain known as the hypothalamus and extend to other parts of the brain that are known to be involved in wake and sleep regulation.

Hypocretin is the key

Hypocretin plays an important part in regulating the sleep-wake cycle by maintaining stable wakefulness and preventing the onset of sleep during the day. If the cells that produce it are destroyed, hypocretin levels are reduced and the sleep-wake cycle is not properly controlled. Most narcolepsy sufferers have undectectable or low levels of hypocretin.

Narcelopsy does not run in families

It is generally not the case that narcolepsy runs in families. There is a particular gene (present in quite a large proportion of the population) that may play a part in narcolepsy, but it is more a case of lower risk for those people who do not have that gene, rather than higher risk for those who do.

The cause is often a minor infection

The cause of narcolepsy is often an infection that “tricks” the immune system into destroying the cells that produce hypocretin by mistaking those cells for attacking bacteria or viruses. The infection might be nothing more than a sore throat or flu-like infection.

Pandemrix – another cause of narcolepsy

Recently, there has been an upsurge in the number of cases of narcolepsy among young people, linked to the use of the swine flu vaccine Pandemrix – see Pandemrix narcolepsy.