Sleep is one of the most important aspects of our life, health and age range. But, 21st century society often ignores it. The consequences are devastating: every major disease in the developed world Alzheimer's, cancer, obesity, diabetes has a very strong causal relationship with sleep deprivation. Until recently, science did not have an answer to the question of why we sleep, or what are its benefits, or why its absence is so detrimental to our health. Compared to other basic impulses in life eating, drinking, and reproducing the purpose of sleep remains elusive. In the book he wrote, Professor Matthew Walker explores his twenty years of cutting edge research to solve the mystery of why sleep matters. By observing all beings from different corners of the world as well as conducting major studies on humans, Why We Sleep investigates everything from what actually happens during REM sleep to how caffeine and alcohol affect sleep and why our sleep patterns change throughout time, altering our appreciation of the incredible phenomena that protect our existence.