On this edition of our show, we speak with Dr. Matthew Walker, a professor of neuroscience and psychology at UC Berkeley, where he directs its Sleep and Neuroimaging Lab. Dr. Walker joins us to discuss his new book, "Why We Sleep: Unlocking the Power of Sleep and Dreams." As per The New York Times Book Review, this book is "a thoughtful tour through the still dimly understood state of being asleep.... [This] is a book on a mission. Walker is in love with sleep and wants us to fall in love with sleep, too. And it is urgent. He makes the argument, persuasively, that we are in the midst of a 'silent sleep-loss epidemic' that poses 'the greatest public health challenge we face in the 21st century.'... 'Why We Sleep' mounts a persuasive, exuberant case for addressing our societal sleep deficit and for the virtues of sleep itself. It is recommended for night-table reading in the most pragmatic sense."