What happens inside your brain when you sleep and dream? We will review recent studies on the nature of nightmares and how medications and diet affect sleep and dreams—and perhaps even discover why we sometimes wake up tired, craving coffee and donuts. Gary Wenk, PhD, is Professor Emeritus of Psychology and Neuroscience at Ohio State University. Along with numerous articles, studies, and books, he is author of The Brain: What Everyone Needs to Know (2017).