Ever wondered why you don’t actually run, fly, or battle dragons in real life while you’re dreaming about it? That’s because your brain has a built-in safety mechanism. During REM (rapid eye movement) sleep—the stage when most vivid dreams occur—your brain temporarily paralyzes your muscles in a process called REM atonia. It’s your body’s way of making sure you stay tucked safely in bed, no matter how wild your dreams get.
But sometimes, this system doesn’t work perfectly. That’s when unusual sleep behaviors, like sleepwalking, can happen. In these cases, the brain’s muscle-paralyzing signals don’t fully kick in, allowing the person to move while still partially asleep. While sleepwalking usually takes place during non-REM sleep, there’s another disorder—REM Sleep Behavior Disorder (RBD)—where people physically act out their dreams, sometimes in sudden or even aggressive ways.
RBD is more common among older adults and is often linked to neurological conditions like Parkinson’s disease. Those with RBD might punch, kick, or fall out of bed mid-dream, often without any memory of it happening. These episodes can pose real risks to both the sleeper and anyone nearby, making diagnosis and treatment essential.
The good news? There are effective treatments, including medications and adjustments to bedtime routines. Creating a safer sleep environment—like removing hard or sharp objects and padding furniture—can also help prevent injuries.
Thankfully, for most of us, the sleep system works as it should. We remain still while our minds explore vivid, sometimes bizarre dream worlds. It’s just one more way the brain looks out for us—even when we’re fast asleep.