It didn’t happen every night, but every now and then, Blake Smith, a 45-year-old writer and programmer from Kennesaw, Georgia, would jolt awake, believing he was under attack. Just what exactly was attacking him was something of a mystery, as it was invisible — a ghost, maybe. Whatever it was, he could feel that it meant him harm.
What was really happening, he now knows, was that he was experiencing sleep paralysis, a phenomenon that occurs either upon falling asleep or awakening and is thought to be a mix-up of normal REM sleep. On the one hand, people who experience it are, in some sense, conscious and aware — they can see that they’re in their bedroom, for example. But some part of their body still thinks they’re asleep — in particular, their muscles are essentially paralyzed, something that happens in REM sleep. It’s thought to be an evolutionary mechanism that prevents people from acting out their dreams.
But in sleep paralysis, this normal function turns terrifying. The experience is often accompanied by some kind of hallucination, usually something scary; people report feeling as if they’re being pinned down by a huge weight on their chest. Washington State University psychologist Brian Sharpless recently published a book on sleep paralysis, in which he argues that the phenomenon may offer up a naturalistic explanation for some terrifying nighttime phenomena found in folklore all over the world — like stories of incubus or succubus attacks. In Zanzibar it’s the popobawa; in Japan it’s called kanashibari; in China it’s known as ghost oppression. “Even though every culture puts its own stamp on it, the core experiences are similar,” Sharpless said. “It’s paralysis — except for the eyes — and conscious awareness during it.” And for most people, it’s incredibly frightening.
It’s not clear exactly how many people experience sleep paralysis, but in one 2011 paper , Sharpless reviewed 35 studies, yielding a combined sample size of more than 36,000 people, and found that about 8 percent of the population has experienced sleep paralysis at least once. “It’s fairly common, but very few people talk about it, and certainly not to their doctors. ‘ Doc, you know, I felt like there was a demonic dwarf sitting on my chest.’ They’re embarrassed by it — they think they’re going crazy,” Sharpless said.
Smith’s own experience of sleep paralysis was one of the major things that nudged him from being a “believer to casual doubter to formal doubter”; he’s now a co-host of theSkeptic magazine podcast ” MonsterTalk .”
Recently Smith spoke with Science of Us about his own real-life monstrous experience with sleep paralysis.