Imagine this: a sickness where millions fell into a deep slumber from which they never woke. Of those that did, many remained trapped in a cage of their own bodies, unable to move or speak but fully aware of the world around them. Imagine that this sickness appeared suddenly, without warning, and spread across the globe, affecting millions in just a few decades. Then, just as quickly as it emerged it disappeared. Survivors were left to suffer, eventually forgotten, while hundreds of questions remained unanswered. This is the story of encephalitis lethargica, the subject of our first ever medical mystery episode. Encephalitis lethargica was a ‘sleepy sickness’ epidemic which afflicted millions in the early 1910s and 20s but has caused only sporadic cases since the 1940s. This mysterious illness revolutionized the fields of neurology and psychiatry and forced physicians to examine where the brain ends and the mind begins. What could cause such an illness and why haven’t we seen it since? Tune in to hear us tell you the story of this fascinating medical mystery.