What is dreaming? What causes dreaming? Why are dreams so strange and why are they so hard to remember? Modern science has given us a new and increasingly clear and complete picture of how dreaming is created by the brain. This picture is important not only for understanding dreaming itself, but also for a science of consciousness and of mental health and illness. This book focuses on dreaming to introduce the reader to sleep laboratory science and to the cellular and molecular mechanisms of sleep. It shows how the new science of dreaming affects theories in psychoanalysis, and how it helps to understand the basis of mental illness.