Dreaming

But when people are awakened during REM sleep they almost always report that they had been experiencing an engaging, realistic, yet often bizarre, sequence of events called a true dream. They were not merely thinking about something; they were actually doing something, and their actions were accompanied by vivid sensory experiences. They were seeing things and hearing things and touching things and moving about as if they were awake.

Fortunately, during REM sleep most motor neurons are inhibited, producing a kind of paralysis that keeps people from hurting themselves during a dream. (People who walk or talk in their sleep do so during Stage 4 sleep, not during REM sleep.)