What is sleep? Brain condition? Physiological process of the body? Or a global phenomenon that can only be understood in the context of ecosystem dynamics? The book talks about the role of sleep at the microscopic level of individual neurons; about how sleep affects each of us and how our behavior affects sleep; about how scientific ideas about sleep were formed in the course of history. Sleep cannot stay beyond serious conversations about the nature of consciousness, ecology, or the future of humanity. The whole world is built around sleep and wakefulness. We live on a half-asleep planet. Sleep is one of the most amazing phenomena, unique states and incomprehensible processes that concern each of us individually and the whole society as a whole. If there was no sleep, the world would be different.