Imagine waking up in the middle of the night to an unearthly figure with blood dripping down its fangs. You try to scream, but you can’t. You can’t move a single muscle! If this sounds familiar, you’ve probably experienced an episode of sleep paralysis, which involves the inability to move or speak upon falling asleep or awakening and is often coupled with hallucinations. About one in five people have had sleep paralysis at least once. But despite its prevalence, it has largely remained a mystery.

For centuries, cultures across the world have attributed these hallucinations to black magic, mythical monsters, even paranormal activity. Sleep paralysis is caused by what appears to be a basic brain glitch at the interface between wakefulness and rapid eye movement (REM) sleep. During REM, you have intensely lifelike dreams. To prevent you from acting out these realistic dreams (and hurting yourself!), your brain has a clever solution: it temporarily paralyzes your entire body.

Indeed, your brain has a “switch” (a handful of neurochemicals) that tilts you between sleep and wakefulness. Sometimes the “switch” fails, however—your brain inadvertently wakes up while your body is still under the “spell” of REM paralysis, leaving you stuck in a paradoxical state between parallel realities: wakefulness and REM sleep. ON THIS DELIVERY, is time to come clean in regards to what I really think about sleep paralysis, as a chronic sufferer of the sleep disorder.