You may take for granted the fact that, no matter how scary a dream may get, in the real world you are actually just sleeping safely in your bed. But that isn’t the case if you have a sleep disorder known as REM behavior disorder (RBD). People who suffer from RBD physically move their bodies while dreaming—and sometimes they even get out of bed and react to what is happening in their dreams.
Dreaming happens during only the REM stage of sleep, a phase of sleep that happens a few times a night. During REM, your brain becomes very active while, at the same time, your body becomes temporarily paralyzed (this helps prevent your body from acting out a dream). However, if you have RBD, the body paralysis doesn’t happen and, as a result, you can move your body even though you aren’t awake. The problem comes when a dream turns violent or scary, since the person who is asleep might end up talking, screaming, jumping out of bed, or punching—behaviors that could harm the person and others. The reason that the paralysis doesn’t kick in hasn’t been figured out yet, but there does seem to be a link between RBD and neurodegenerative diseases like Parkinson’s disease.
RBD comes on suddenly and the majority of people who have it are men who are older than 50 (but it has been known to happen to much younger people). RBD doesn’t necessarily affect everyone in the same way. It can happen every now and then or multiple times every night and it can also get worse over time. To get diagnosed with RBD, you will likely need to spend the night in a sleep clinic hooked up to monitors and being studied. This is the only way to confirm that paralysis isn’t happening during REM sleep—the main signifier of RBD. The good news is that RBD is very treatable once diagnosed: Prescription medication can improve RBD in about 90 percent of cases.