possible answer: "The activation-synthesis model of dreaming says that dreams are a meaningless by-product, or epiphenomenon, of sleep. The theory claims that during REM sleep, the brain’s neurons are firing in the lower brain centers, which send information to the cortex, or the part of the brain that makes sense of inputs during normal consciousness. When the cortex tries to make sense of the stream of inputs it receives during sleep, we experience a dream."
