For most of us, dreaming is purely a mental activity. Dreams occur solely in the mind while the body is at rest. In fact, the muscles are temporarily paralyzed, preventing any kind of movement. Not so for those who suffer rapid eye movement sleep behavior disorder (RBD). They act out their dreams, talking, screaming, hitting, punching or jumping out of bed without realizing they are doing so. “The only sensations the sleeper experiences are what is occurring in their dream,” says the National Sleep Foundation. If a person with RBD is having a violent dream, they may unwittingly injure their sleeping partner.
Doctors aren’t sure exactly why it happens, but Dr. Walia said it’s likely related to problems with the nerve connections that are supposed to freeze the muscles while dreaming.