In recent years neuroscientists have uncovered the countless ways our brain trips us up in day-to-day life, from its propensity toward irrational thought to how our intuitions deceive us. The latest research on sleep, however, points in the opposite direction. Where old wives tales have long advised to "sleep on a problem," today scientists are discovering the truth behind these folk sayings, and how the busy brain radically improves our minds through sleep and dreams. In The Secret World of Sleep, neuroscientist Penny Lewis explores the latest research into the nighttime brain to understand the real benefits of sleep. She shows how, while our body rests, the brain practices tasks it learned during the day, replays traumatic events to mollify them, and forges connections between distant concepts. By understanding the roles that the nocturnal brain plays in our waking life, we can improve the relationship between the two, and even boost creativity and become smarter. This is a fascinating exploration of one of the most surprising corners of neuroscience that shows how science may be able to harness the power of sleep to improve learning, health, and more.