In Dreaming Souls, Owen Flanagan provides both an accessible survey of the latest research on sleep and dreams and a compelling new theory about the nature and function of dreaming. Flanagan argues that while sleep has a clear biological function and adaptive value, dreams are merely side effects, 'free-riders', irrelevant from an evolutionary point of view. But dreams are hardly unimportant. Indeed, Flanagan argues that dreams are self-expressive, the result of our need to find or create meaning, even when we are sleeping.