What Is a Dream?

Abstract

Dreaming happens during sleep. When we aren’t interacting with the world, our minds turn inwards. We dream. These dreams differ. Rapid eye movement (REM) dreams are visual, vivid, bizarre, emotional, and highly associative with embodied narratives, whereas non-rapid eye movement (NREM) dreams tend to be shorter and more thought-like. During REM dreams, the brain is as active, or even more active, than it is during wakefulness. In some dreams, during REM sleep, the dreamer is lucid—they become aware they are dreaming and can, sometimes control the dream content. These different types of dream happen at different times in the sleep cycle. Across the night, we experience NREM sleep (including light sleep and deep sleep) and REM sleep in a fixed sequence. The night isn’t a uniform period of rest. This introductory chapter explains these basic issues about sleep and dreams.