Encephalitis Lethargica: During and After the Epidemic is akin to a detective novel about a major medical mystery that remains unsolved. During the 1920s and 1930s a strange, very polymorphic condition affected much of the world although not at the same time everywhere and certainly not with the same symptoms. This condition, encephalitis lethargica, could cause death in a short period, or a Rip Van Winkle type of sleep that might last days, weeks or months, but could also, surprisingly, cause insomnia. Its symptoms were thought to encompass almost anything imaginable, which made its...