The first sleep theory by Professor Matthew Walker, director of the Sleep and Neuroimaging Laboratory at the University of California, Berkeley.

Sleep is one of the most important yet least understood aspects of our lives, health, and longevity. Until very recently, science had no answers to the questions of why we sleep, what good sleep can do, and why not sleeping can have devastating effects on our health. Compared to the other basic life activities of eating, drinking, and reproducing, the purpose of sleep remained elusive.

An explosion of scientific discoveries in the past two decades has shed new light on this fundamental aspect of our lives. Matthew Walker, a preeminent neuroscientist and sleep expert, gives us a new understanding of the importance of sleep and dreams. In the brain, sleep enhances our ability to learn, remember, and make logical decisions.

It recalibrates emotions, replenishes the immune system, fine-tunes metabolism, and regulates appetite.

Dreaming relieves painful memories and creates a virtual reality space in which the brain merges past and present knowledge to stimulate creativity.

How do caffeine and alcohol affect sleep? How do caffeine and alcohol affect sleep? Why do our sleep patterns change throughout life? How do common sleep aids affect us and cause long-term damage? Walker illustrates cutting-edge scientific breakthroughs and synthesizes decades of research and clinical practice to show that leveraging sleep can improve learning, mood, and energy levels; regulate hormones; prevent cancer, Alzheimer's, and diabetes; slow the effects of aging; increase longevity; improve children's education and longevity; and increase business efficiency, success, and productivity. Clear-eyed, engaging, and accessible, "Why People Sleep" is an extremely important and thought-provoking book.