We spend a third of our lives asleep. Every organism on Earth—from rats to dolphins to fruit flies to microorganisms—relies on sleep for its survival, yet science is still wrestling with a fundamental question: Why does sleep exist? During Shakespeare and Cervantes’ time, sleep was likened to death, with body and mind falling into a deep stillness before resurrecting each new day. In reality, sleep is a flurry of action. Trillions of neurons light up. The endocrine system kicks into overdrive. The bloodstre
Hide player controls
Hide resume playing