Dreams are thoughts, emotions and the images shaped by them, which are encountered when asleep. One has dreams during the rapid eye movement sleep. Various theories on dream interpretations exist but the real purpose of dreams is still unknown. Dreams are closely associated with human psychology. Research shows that during an average lifespan, a human being spends about six years in dreaming which is around two hours every night. Here's a gist of what dream psychology says about why people have dreams and how to interpret them.