What causes narcolepsy?

The exact cause of narcolepsy is still largely unknown but most patients are thought to have a deficiency of the neuropeptide called hypocretin.

Sleep-wake cycle and the role of hypocretin

• It is known that severe disruption of the normal sleep-wake cycle is responsible for the symptoms in narcolepsy. Abnormalities of REM or dream sleep are particularly important
• A neuropeptide known as hypocretin or orexin is normally responsible for controlling the sleep-wake cycle by maintaining stable wakefulness and preventing the onset of sleep during the day
• The cells containing 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
• Most narcolepsy sufferers, however, have undectectable or low levels of hypocretin which leads to the disruption of the sleep-wake cycle
• The cause of the low number of cells containing hypocretin is unknown but it has been suggested that the body’s immune system which normally attacks infections may also destroy the hypocretin cells by mistake, and that narcolepsy is a so-called autoimmune disease
• It is rare for narcolepsy to run in families although a normal variation in a subjects’s chromosomes may confer a higher risk of developing the disease