Ever wonder why you don’t physically act out your dreams—like running, jumping, or even fighting off imaginary monsters? That’s because during a stage of sleep called REM (rapid eye movement), your brain activates a protective mechanism that temporarily paralyzes your muscles. This state, known as REM atonia, keeps your body still while your mind explores vivid dream worlds.
It’s your brain’s way of keeping you safe.
But sometimes, that system doesn’t work as it should. When the paralysis fails to fully engage—or kicks in at the wrong time—you get sleep disorders like sleepwalking or REM Sleep Behavior Disorder (RBD). In these cases, people may talk, move, or even walk around while still asleep, often with no memory of it afterward.
Sleepwalking usually happens during deep, non-REM sleep, and is more common in children. RBD, on the other hand, occurs during REM sleep and can cause people to physically “act out” their dreams—sometimes with dramatic or even dangerous movements.
While these conditions can be unsettling, they are treatable. Medications, stress management, and creating a safe sleep environment can make a big difference.
So the next time you wake from a wild dream, be thankful for that built-in safety switch. Most of the time, your brain knows exactly how to keep the action on the dream stage—and out of your bedroom.