What happens to the body during REM sleep?

During REM (Rapid Eye Movement) sleep, the body undergoes a unique physiological state characterized by various activities. One of the most notable features is that the body becomes immobilized due to atonia, a temporary loss of muscle tone. This paralysis of the voluntary muscles prevents the individual from acting out dreams, which often occur during this stage of sleep. The immobilization is crucial for safety, as it protects the sleeper from harm caused by potentially acting out vivid dreams.

This state of atonia is a natural mechanism that occurs during REM sleep and is a component of the sleep cycle that distinguishes it from other stages of sleep, where muscle tone is less affected. Thus, the immobilization of the body during REM sleep serves an important protective function while allowing the brain to engage in vivid and complex dream activity.