Imagine waking up in pitch darkness to a slavering monster with blood dripping down its fangs. You try to cry out for help but can’t. You’re paralyzed from head to toe! Sleep paralysis—paralysis upon falling asleep or awakening often coupled with uncanny “ghost” sights—is surprisingly common yet steeped in mystery.
One in five people worldwide are affected by these visceral nightmares. But despite its prevalence, it has largely remained a riddle. For millennia, these visions have left diverse imprints on human culture, from
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Sleep paralysis is triggered by a basic brain glitch at the interface between wakefulness and rapid eye movement (REM) sleep. During REM you have crisp, life-like dreams. To prevent you from acting out these vivid dreams and hurting yourself, your brain temporarily incarcerates your entire body. This neural safety procedure is tightly controlled by a handful of chemicals released from the lower part of your brain that flip-flop you between sleep and wakefulness. This chemical switch works smoothly in a winner-take-all manner most of the time: either you remain in a deep slumber, or you awaken, fully conscious. But not always. Sometimes you wake up while still under the spell of REM paralysis, leaving you stuck in the middle of sleep and wakefulness. As if being paralyzed and unable to speak when waking up isn’t sufficiently nerve-racking, occasionally, the terrifying dreams of REM can “spill over” into conscious awakening, like dreaming with your eyes open. These baffling sights occurring around the edges of sleep have left helpless spectators horrified throughout history.
Indeed, as many as
These nocturnal encounters are interpreted differently around the globe. Each culture provides its own bizarre twist. In Egypt, my research shows that sleep paralysis is thought to be triggered by
These explanations—scientific and supernatural—can have a major say on how people experience sleep paralysis. When directly comparing sleep paralysis in Egypt and Denmark, my team and I found that Egyptians fear it much more than Danes do. That is, a staggering 50% plus Egyptians were convinced that their
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The question naturally came up, could the findings be replicated? That is, could we possibly show, in another culture, that these beliefs about sleep paralysis, could exacerbate the experience. Italy was a good place to go hunting for scientific answers. Recall Italians also have florid ideas about the origin of sleep paralysis. According to one of our studies, over a third of people from Italy’s Abruzzo region believe their sleep paralysis may have been caused by the Pandafeche. Like Egyptians, we soon discovered that
But how does it all work? In a nutshell, anxiety predisposes people, so that if you fear it, you’re also more likely to experience it, and the greater its effects are. A key clue comes from our finding that sleep paralysis is nearly twice as common in Egypt compared with Denmark. Likewise, Italians who think their sleep paralysis may have a supernatural origin are also
Indeed, our discoveries suggest that sleep paralysis, if coupled with certain beliefs, isn’t just petrifying but also traumatizing. Intriguingly, in
As we’re exploring sleep paralysis around the world, the riddle remains. Here is a condition that can make you see ghosts, witches, and menacing monsters, even exotic animals, of various flavors, depending on the corner of the globe you occupy. It shows how a singular phenomenon in science can leave a myriad of imprints on culture. And perhaps more importantly, it shows how our beliefs can color the very lens through which we view the world, illustrating the sometimes terrifying, power of human imagination.