Narcolepsy is a mysterious disorder that involves sudden, uncontrollable sleepiness, among many other symptoms. On one hand, its cause seems straightforward: people slowly lose a special group of neurons that produce hypocretin, a hormone that keeps us awake.
But what kills the neurons?
Many scientists have long suspected that the immune system is responsible. That would make narcolepsy an autoimmune disease–one in which a person’s immune system turns on their own healthy cells.
There’s been a lot of evidence to support this idea, but a team of scientists from Stanford University have finally found what they describe as a “smoking gun”. People with narcolepsy, and only people with narcolepsy, have a special group of immune cells that targets hypocretin. These cells might be attacking the neurons directly, or acting through an intermediary, or something else altogether. Either way, it’s the first clear, direct sign of autoimmunity.
The study also helps to explain some puzzling quirks about narcolepsy, like why the 2009 swine flu pandemic led to a surge of cases in China, or why one particular vaccine against that strain did the same in Europe.
The details are fascinating, and I’ve written about them for Nature. Head over there for the full story.