Questions on the origins and meaning of dreams are as old as humankind, and as confounding and exciting today as when nineteenth-century scientists first attempted to unravel them. Why do we dream? Do dreams hold psychological meaning or are they merely the reflection of random brain activity? What purpose do dreams serve? addresses these core questions about dreams while illuminating the most up-to-date science in the field. Written by two world-renowned sleep and dream researchers, it debunks common myths that we only dream in REM sleep, for example—while acknowledging the mysteries that persist around both the science and experience of dreaming. Antonio Zadra and Robert Stickgold bring together state-of-the-art neuroscientific ideas and findings to propose a new and innovative model of dream function called NEXTUP—Network Exploration to Understand Possibilities. By detailing this model’s workings, they help readers understand key features of several types of dreams, from prophetic dreams to nightmares and lucid dreams. reveals recent discoveries about the sleeping brain and the many ways in which dreams are psychologically, and neurologically, meaningful experiences; explores a host of dream-related disorders; and explains how dreams can facilitate creativity and be a source of personal insight. Making an eloquent and engaging case for why the human brain needs to dream, offers compelling answers to age-old questions about the mysteries of sleep.