The sleep disorder narcolepsy is linked to immune-system genes and is caused by the loss of neurons that express the protein hypocretin. Hypocretin-targeting immune cells have now been found in people with narcolepsy.
The events that lead to the sleep disorder narcolepsy are a long-standing mystery. Writing in Nature, Latorre et al.1 reveal that people with narcolepsy have unusually high levels of a type of immune cell called a T cell, which targets proteins normally present in neurons in the brain. This finding raises the question of whether narcolepsy arises because T cells unleash an autoimmune response against neurons that are important for sleep regulation.
