In this episode, my guest is Dr. Matt Walker, Professor of Neuroscience and Psychology and the Founder and Director of the Center for Human Sleep Science at the University of California, Berkeley. He is also the author of the international bestselling book Why We Sleep and the host of “The Matt Walker Podcast.” We discuss the biology of sleep, including its various stages and what specifically happens to those stages when we don’t get enough sleep. We also discuss the effects of sunlight, caffeine, alcohol, naps, hormones, exercise, marijuana, sexual activity and various supplements on sleep. The episode consists of both basic science information and many science-supported actionable tools.