Sleep has long been a topic of fascination for artists and scientists. Why do we sleep? What function does sleep serve? Why do we dream? What significance can we attach to our dreams?We spend so much of our lives sleeping, yet its precise function is unclear, in spite of our increasing understanding of the processes generating and maintaining sleep. We now know that sleep can be accompanied by periods of intense cerebral activity, yet only recently has experimental data started to provide us with some insights into the type of processing taking place in the brain as we sleep. There is now strong evidence that sleep plays a crucial role in learning and in the consolidationof memories. Once the preserve of psychoanalysts, 'dreaming' is now a topic of increasing interest amongst scientists. With research into sleep growing, this volume is both timely and valuable in presenting a unique study of the relationship between sleep, learning, and memory. It brings together ateam of international scientists researching sleep in both human and animal subjects. Aimed at researchers within the fields of neuroscience, cognitive neuroscience, psychiatry, and neurology, this book will be an important first step in developing a full scientific understanding of the most intriguing state of consciousness.