No one knows with any certainty what the causes of narcolepsy are.
Starting in the 1970s at the Stanford Medical Center, a doctor Emmanuel Mignot, began research that involved the breeding of narcoleptic dogs in an effort to pinpoint narcolepsy causes in humans. In 1999, a mutation of a specific gene, hypocretin, was pinpointed as the cause of the dogs' narcolepsy.
Around the same time in Texas, a medical researcher named Masashi Yanagisawa along with a group of scientists, was working on an unrelated research project involving mice. Quite accidentally, they determined that the same gene, but one which Yanagisawa had named orexin, was linked to the sleep-wake cycles in the mice which, when "knocked out" or removed from the mice, produced a condition very similar to human narcolepsy.
These two findings - that a lack of the gene hypocretin / orexin is responsible for narcolepsy in animals, triggered a frenzy of further research and study on the subject.
From that point to today, three hypotheses have been put forth about the possible causes of narcolepsy in humans.
That however, brings us back to the short answer about the causes of narcolepsy: no one knows for sure. Research is still ongoing and, although there may be treatments for narcolepsy, there is no cure for narcolepsy and to date, no solid evidence as to what causes narcolepsy.
An autoimmune disorder is a condition where an individual's own immune system, thinking that it's attacking a foreign virus, starts attacking healthy cells.
If you suspect that you, or someone you know, may be suffering from the sleep disorder narcolepsy, explaining your symptoms will help your doctor diagnose your condition. While there is no cure, there are definitely treatments that will alleviate many of the symptoms of narcolepsy.