The Science Of Sleep Paralysis : Short Wave As a teenager, Josh Smith was plagued by sleep paralysis. Now he's afraid his kid might be experiencing it too. In this listener questions episode, Josh asks what the science says about this sleep disorder and what he can do to help his son.
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Seeing Monsters? It Could Be The Nightmare Of Sleep Paralysis

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Seeing Monsters? It Could Be The Nightmare Of Sleep Paralysis

Seeing Monsters? It Could Be The Nightmare Of Sleep Paralysis

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  • <iframe src="" width="100%" height="290" frameborder="0" scrolling="no" title="NPR embedded audio player">
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You're listening to SHORT WAVE from NPR. Maddie Sofia here with SHORT WAVE reporter Emily Kwong. And today - another listener question episode.


SOFIA: Whoop, whoop.

KWONG: Thank you for your questions. We genuinely love trying to answer them.

SOFIA: Today, we're hearing from Josh Smith from Orange, Calif.

KWONG: All right, Maddie. So Josh sent this fascinating note about these strange episodes he'd have at night starting when he was 5 years old where he'd wake up, but his body would remain frozen.

SOFIA: I don't like that.

KWONG: It gets worse. So these episodes really escalated when he was a teenager when his home life got really stressful. There was this one night when he was about 16, he woke up in the pitch black.

JOSH SMITH: I couldn't move my head, couldn't move my arms, my legs. And I could sense there was a presence in the room. And I, you know, started freaking out because I couldn't move. I couldn't speak.

SOFIA: Like, he couldn't move at all?

KWONG: Not at all - but his eyes were open. And after a minute or two, that presence he felt in the room started to float towards him.

SMITH: It was humanoid. And it was pale white, like, no pigment in the skin, no eyebrows, you know, no facial hair, no nothing. But the eyes - I remember very specifically that whatever this thing was, the eyes were the deepest of deep just darkness.

KWONG: And he couldn't move. But he actually felt this huge pressure on his chest. And Josh thought, this has to be a demon. The figure came basically right up to his face.

SMITH: It stayed there for maybe 15, 20 seconds. And then, you know, growing up in an evangelical home, you know, I was told, hey, just say the name of Jesus, you know? So I started saying the name of Jesus over and over and over.

KWONG: Saying it in his head.

SMITH: And then it went away. And I woke up.

SOFIA: OK, Kwong. What?

KWONG: (Laughter) Yeah, really, right? Biggest question mark. What was going on?

SOFIA: Right.

KWONG: Josh was likely in the grip of what's known as sleep paralysis.

SOFIA: I've heard of that.

KWONG: Like a lot of people with sleep paralysis, Josh was never formally diagnosed. But he had all the signs - total immobility upon waking up at night, that feeling of terror and, occasionally, hallucinations - seeing things or hearing things or sensing things that weren't there. And Josh went through this over and over and over again as a teenager, but his parents weren't exactly clued in on what to do.

SMITH: If you came to them with a nightmare, they would lock their door and tell you to go back to bed, you know?

KWONG: And the real reason Josh wrote to us is because he's a dad now. And he's worried about his own son having sleep paralysis. So he wants to better understand this condition.

SMITH: I want to be able to be there for, you know, my kid and say, like, hey, this is what's going on, that everything's going to be OK.

SOFIA: He sounds like a good dad.

KWONG: I think so. Yeah.


SOFIA: So today on the show, we talk about how sleep paralysis holds the body hostage.

KWONG: And how to help yourself or the person in your life who may be fending off these hallucinations, these monsters in their sleep.


SOFIA: All right, Kwong. The science of sleep paralysis - where do you want to start?

KWONG: I want to start at lights out...


KWONG: ...That moment when you hit the pillow.

SOFIA: Oh...

KWONG: Close your eyes (laughter)...

SOFIA: ...I see.

KWONG: ...And start to drift off to dreamland, as told in the dulcet tones of Clete Kushida.

CLETE KUSHIDA: When we hook up electrodes to the head to look at the brainwave activity, we actually see that the brainwaves start slowing down in frequency.

KWONG: Clete Kushida is a neurologist at the Stanford Sleep Medicine Center.

SOFIA: I'm so soothed.

KWONG: As you should be. We're going to sleep. Your heart rate slows. Your muscle activity decreases. And after an hour, hour and a half of this, as you fall deeper and deeper down the rabbit hole of slumber, you embark on the most memorable part of the sleep cycle, REM sleep - rapid eye movement sleep.

SOFIA: When your little eyes dart back and forth.

KWONG: Yes. When you dream, your brain actually perks back up. In fact, the brain activity of a person in REM sleep is comparable to that of an awake person. But the difference is that your voluntary muscles, except for those that control eye movements, are paralyzed. Your brain is saying, hey, body, stop moving right now.

KUSHIDA: The spinal motor neurons that connect the spinal cord to the muscles - as a person falls asleep, what happens is that those spinal motor neurons are actually inhibited.

SOFIA: So your body's just, like, naturally paralyzed when it's asleep?

KWONG: During REM sleep, yeah. You may twitch, but overall, your brain wants your body to be still. But imagine waking up in this state and not being able to move a muscle.

SOFIA: I am not relaxed anymore.


KUSHIDA: They'll either be going into sleep or coming out of sleep. And they can't move.

KWONG: Your mind is awake, but your body is asleep. That's sleep paralysis. You know how Josh felt like he couldn't get up? Some people report difficulty breathing in these episodes. And that pressure on the chest is because he's noticing that normal reduction in respiratory activity, which is perfectly healthy during REM sleep, but really strange to feel when you've woken up and can consciously experience it, you know?

SOFIA: Yeah. Yes, I do.

KWONG: And Clete says that about 75% of the time, those in sleep paralysis will hallucinate.

KUSHIDA: Most of the time we'll hear that it's something frightening or disturbing. But, you know, there have been instances where a person will report that, you know, they just hallucinated that one of their loved ones was there.

SOFIA: Like a ghost?

KWONG: You know, a lot of paranormal activity could be explained by sleep paralysis. These hallucinations have been interpreted differently across cultures. In Newfoundland, it's known as Old Hag, a witch sitting on your body. In Japanese folklore, sleep paralysis is called kanashibari, which means bound in metal.

SOFIA: I had no idea. This is very fascinating. So it's fairly common, then?

KWONG: It appears so. You know, reviewing scientific studies across 50 years, researchers in Pennsylvania estimated that 8% of the general population has at least one episode of sleep paralysis in their lifetime. But those numbers are way higher in certain populations. In fact, sleep paralysis is most common in teenagers.

SOFIA: Oh, my God. Being a teenager is the worst.


SOFIA: So do scientists know what causes it?

KWONG: Not really. It has something to do with neurotransmitters in the brain not behaving the way they're supposed to, not allowing the muscles to move when a person is coming out of REM sleep. But like I said, certain populations experience it more - meaning there are certain conditions that make a person more inclined to an episode of sleep paralysis. So for instance, it's really common in those with narcolepsy.

SOFIA: Narcolepsy - like, people who suddenly fall asleep in the middle of the day?

KWONG: Exactly. Yeah. Sleep paralysis is actually considered a symptom of narcolepsy...


KWONG: ...So there's that. But it also crops up in those with panic disorders, certain psychiatric disorders, populations that have experienced trauma and those with poor sleep for all kinds of reasons - like shift workers and students, those with jetlag. With all these groups, you could say stress is a common thread. But treatment can look different depending on who you are.

SOFIA: This - I feel like this has to take, like, a huge toll on your waking life.

KWONG: Especially if you have these episodes over and over and over again.

SOFIA: Like our listener, Josh.

KWONG: Yeah. He told us he'd actually avoid sleep as a teenager for fear of seeing this demon. He spent his late teens numbing himself with video games, going on the Internet until he passed out.

SMITH: I remember towards the end, there was a couple times I just laughed at the demon...

KWONG: Like, laughed in his head.

SOFIA: Yeah.

SMITH: ...Where I'd just be like, you know, dude, come on. Go away. I can't - like, I'm too stressed right now. I can't deal with you right now (laughter).

KWONG: Josh is 28 now. He hasn't experienced an episode of sleep paralysis in four years.

SOFIA: What changed?

KWONG: He found ways to significantly reduce the stress in his life, at home, at work. And he thought the specter of sleep paralysis was well in his rearview mirror until a few weeks ago when his 13-month-old son woke up but didn't cuddle into his dad like he normally does...

SOFIA: Oh, no.

KWONG: ...And it raised some concerns.

SMITH: He just kind of went limp. And it scared me.

SOFIA: Little dude.

KWONG: Yeah. Seemed a little too familiar. His son wasn't moving. His mouth was in this O-shape, kind of slack. His eyes were open, but he didn't seem to be tracking on anything.

SMITH: I tried to motion towards him and whatnot like, hey. You know, buddy, hey, wake up.

KWONG: And I should add, this happened a few weeks ago. But it also happened when Josh's son was 3 months old.

SOFIA: So it's happened twice that he knows of.

KWONG: So we posed this to Clete, our sleep doctor. He said it's hard to say what's going on without seeing Josh's son himself. Sleep paralysis is possible. But it could be another kind of sleep disorder, too, like narcolepsy or confusional arousal - when a person wakes up really disoriented - or sleep terrors, which are, in fact, more common in children.

SOFIA: Yeah. I feel like sleep disorders are really complicated.

KWONG: Truly. So honestly, Clete's first takeaway is that if you suspect someone is going through this to just keep an eye on any potential episode and provide comfort in those moments because it is pretty scary.

KUSHIDA: So the main thing is reassurance because in most cases it just spontaneously disappears. But if it happens repetitively, then they should have it checked out by either a sleep specialist or neurologist.

KWONG: So a second takeaway is that if these episodes persist, go to a sleep clinic where doctors can run a study, make a diagnosis or refer you or that patient to another specialist to tackle what's at the root of sleep paralysis, whether it's stress or something else.

SOFIA: Is it possible that Josh's son inherited this from his dad?

KWONG: Well, sleep paralysis has been shown to run in families, but its genetic markers have not been identified yet. Clete wants to see it figured out, though, because sleep really impacts quality of life. And this can be terrifying to go through all by yourself. You know, when I called Josh to pass along this information to him, our fine listener, he said, I just want to give our son the tools I didn't have to navigate these episodes or whatever else is going on.

SOFIA: That's really nice.

KWONG: Yeah.


SOFIA: All right. Thank you, Emily Kwong. And thank you to Josh Smith for sharing his story for this listener episode.

KWONG: Please write us your listener questions. We'd love to hear them and do our very best to answer them.

SOFIA: You can send them to

KWONG: Today's episode was produced by Rebecca Ramirez and edited by Viet Le.

SOFIA: I'm Maddie Sofia.

KWONG: I'm Emily Kwong.

SOFIA: You're listening to SHORT WAVE from NPR.

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