JAD ABUMRAD: I'm Jad Abumrad.

ROBERT KRULWICH: [snoring]

JAD: Are you asleep? Hey!

ROBERT: Hi.

JAD: Do you even know where you are right now?

ROBERT: Did you see what I did with my leg?

JAD: What?

ROBERT: I kicked myself awake. Did you see that?

JAD: I heard it. I'm Jad Abumrad.

ROBERT: Oh, I'm Robert Krulwich.

JAD: And our next falling feature is ...

ROBERT: Is falling asleep, but with a little kick.

JAD: This is Radiolab.

FREDERICK COOLIDGE: Let's do it.

JAD: Well, tell me your name first, and just tell me how you would like to be identified on air.

FREDERICK COOLIDGE: You can call me Fred. I like it the best.

JAD: Okay.

FREDERICK COOLIDGE: My full title is Professor Frederick L. Coolidge, University of Colorado at Colorado Springs.

JAD: So just so we get our definitions right, what is a hypnic jerk?

FREDERICK COOLIDGE: It appears to be this—what seems to be a reflex. Everybody's experienced it. It's you're still semi-conscious, then you start to feel kind of dreamy. You start to feel this loosening of your thoughts, loosening of your reality.

ROBERT: Hmm.

JAD: But just as you're about to go under, he says ...

FREDERICK COOLIDGE: Just at the first onset of sleep ...

JAD: Bam!

FREDERICK COOLIDGE: One big jerk.

JAD: And then you're ...

FREDERICK COOLIDGE: Awake.

JAD: Usually you wake up with this feeling of like, "Oh, my God! Oh, my God! Oh, my God! Oh, all right."

FREDERICK COOLIDGE: And, you know ...

JAD: Wait, how did you start studying this?

FREDERICK COOLIDGE: I was working at Kentucky Fried Chicken. Can I say that on the air?

JAD: Yeah, of course.

FREDERICK COOLIDGE: For a dollar an hour, and I just thought, "Man." I still can't eat coleslaw to this day, because I would do 100 pounds of coleslaw a day. So I saw this ad on campus, and it said, "Somebody to work in a sleep lab." So I went and applied, and I ended up in the beginning cleaning toilets, but I just got into all of sleep. I thought it was fascinating. And I got fascinated by these giant jerks at the beginning of sleep, and I said, "What is that?" You know? And they said, "Oh, that's a hypnic jerk." I said, "What is that?" And they said, "That's a hypnic jerk."

JAD: [laughs]

JAD: In other words, no one could really explain to him why these things happen.

FREDERICK COOLIDGE: That's right.

JAD: So he started poking around, and there were some theories, you know, having to do with, like, physiological changes in your body.

FREDERICK COOLIDGE: You know, a lowering of oxygen content or something like this.

JAD: But that kind of explanation didn't really satisfy.

FREDERICK COOLIDGE: It really doesn't say well, why? What was its function? And as I started to look at the literature, I saw that we had a very long history sleeping in trees. If we go back to Australopithecus afarensis—this is Lucy—three million years ago. Lucy was bipedal. I mean, walking on two legs.

JAD: Lucy lived in the trees, but unlike the other primates, she would sometimes go down to the ground.

FREDERICK COOLIDGE: But on the ground, you've got big birds, you've got snakes, tigers and reptiles. That ground life was stressful, but at night she crawled up the tree for safety. She climbs up in that tree, drops food there for her baby, and she's gonna drop off to sleep.

JAD: Her muscles loosen, her hands uncurl.

FREDERICK COOLIDGE: She starts to have that relaxation.

JAD: Pretty soon she can't feel the tree under her back or hear the noises down below.

ROBERT: Hmm.

JAD: Stay with me, Krulwich.

ROBERT: Okay.

JAD: She feels like she's floating—or falling.

FREDERICK COOLIDGE: Lucy! Falling! Falling!

JAD: That means ...

[animal growling]

FREDERICK COOLIDGE: It might be a real good idea to wake up from that. Sleep was such a dangerous proposition for so many millions of years that something like the hypnic jerk, if some of those primates had that behavior, they may have been just slightly more likely over millions of years to adapt and survive.

JAD: We haven't gotten rid of it yet is what he's saying.

ROBERT: So that's my trick is just basically so I don't get eaten by a lion all these many years ...?

JAD: Yeah, that's what he's saying. It's sort of like a Lucy echo.

ROBERT: Do we know this, or are we just imagining?

JAD: No, how are we gonna know this? This is just a story. But there's at least one tantalizing bit of evidence to support this idea.

FREDERICK COOLIDGE: You ask college students what are the most common dreams that you have, and falling is number one or number two most common theme. And if you go on a college campus, you know, thanks to OSHA, right? You have no chance of falling off anything. They'll make sure that your fullest drop is like a foot or six inches. Even then, it'd have big yellow and red signs all over it. But they dream of falling? What?

JAD: And by the way, the next most common dream after falling is being chased by an alien in a blue dress.

ROBERT: No it isn't.

JAD: Is too.

[ARCHIVE CLIP, woman: You're walking, and you don't always realize it, but you're always falling.]

DAVID EAGLEMAN: Well actually, I have a random one for you guys about falling. As I was driving over here I was thinking about it.

JAD: Okay.

[ARCHIVE CLIP, woman: With each step ...]

JAD: Neuroscientist David Eagleman again.

[ARCHIVE CLIP, woman: ... you fall forward slightly, and then catch yourself ...]

DAVID EAGLEMAN: I started wondering, what happens ...

[ARCHIVE CLIP, woman: ... from falling.]

DAVID EAGLEMAN: Why is it that elderly people fall down a lot? If you go into any hospital ward, you'll see lots and lots of elderly people who are in there with broken hips and things like that because they've—they've fallen. I started asking my clinician friends, and they say, "Well, they have a poor sense of balance, muscle weakness," and so on. I said, "Could it have anything to do with timing?"

JAD: What do you mean?

DAVID EAGLEMAN: Well, one of the things I study is how the brain sends out signals to the whole body, and how these signals come back. Because the strange part is the brain is situated all the way at one end of the body, all the way at the top end, and it's controlling this huge amount of machinery. You have to send signals all the way out to the toes and all the way back, and they're surprisingly slow in the brain. It's about 300,000 times slower than signals move around in a computer.

JAD: Hmm.

DAVID EAGLEMAN: So it would be like if you were a NASA operator controlling the Mars Rover, there's a delay between when you send the signals and when you get the feedback. And so what happens is the brain is very—puts a lot of effort into making sure that it knows exactly the timing of sending signals out and when it's getting signals back. And that's how you walk, for example.

[ARCHIVE CLIP, woman: Do you want the camera? Cathy, get the camera.]

ROBERT: So this is like what toddlers learn in reverse. Aren't they learning the timings to get the left foot out in front of the right?

DAVID EAGLEMAN: That's exactly what they're doing. They're calibrating the timing of their whole nervous system.

JAD: That's interesting, because my kid's 10 months old, and I think he's in this calibrating period. What's happening with him now is he's standing, but then it looks like he's about to take a step, but then right as he's about to—oh!

[ARCHIVE CLIP, woman: Oh, that was good!]

JAD: So basically you're saying his little brain is trying to figure out the timings of electricity racing from brain to foot and foot back to brain.

DAVID EAGLEMAN: Yes.

JAD: Mission control is going, "Okay, we're sending that message to the feet. We expect it back in 300 milisec ..."

[ARCHIVE CLIP, Jad: Oh!]

JAD: Tumble, fall.

[ARCHIVE CLIP, woman: Take three.]

JAD: Okay, we're gonna try now 280 milliseconds. Okay, 280, go!

[ARCHIVE CLIP, Jad: Oh!]

JAD: Tumble, fall.

DAVID EAGLEMAN: That's exactly right. A lot of trial and error until you get the timing right.

ROBERT: But get it right, now you're a walker.

DAVID EAGLEMAN: Right.

[ARCHIVE CLIP, woman: Three, four. How many—oh my God! You're, like, running!]

DAVID EAGLEMAN: Now something that happens in, let's say, multiple sclerosis ...

JAD: And maybe also when you get old, says David.

DAVID EAGLEMAN: ... is that the timing starts to change because there's damage to the sheathing around the nerves, and that slows down certain signals. So then the brain says, "Oh, I thought my foot should have hit the ground by now but it hasn't. So I'm gonna send out a corrective motor command." And then finally signal does come back, and you've sent out this corrective motor command, and you'll stumble.

[ARCHIVE CLIP, woman: With each step you fall forward slightly, and then catch yourself from falling.]

ROBERT: Now we're going to fall far from home. We're gonna have to travel a good many light years off the planet to fall in this particularly special and gruesome way. Our faller is Neil deGrasse Tyson, he's an astronomical physicist.

JAD: Is that what he is?

ROBERT: Yeah.

JAD: Here he is at the Herbst Theater—I like saying that. Herbst Theater in San Francisco, in front of an audience talking about ...

ROBERT: Falling apart.

NEIL DEGRASSE TYSON: I'm minding my own business on the airplane, and someone looks and sees what I'm doing. They find out I do astrophysics, then out come the questions, "When will life end? Will the asteroid come? Will the Aztec calendar destroy the Earth?" There's all—there's—it goes on and on, so I figured people like death and mayhem. So I might as well title the book with that because there's a whole chapter on how to die as you fall into a black hole, which I personally think is a kind of cool way to die. Because what happens is the gravity of the black hole is extreme, as you can imagine. Light doesn't even escape, its gravity is so extreme. Light traveling at the speed of light, right? So if light doesn't come out, nothing's coming out. It's black, you fall in, you're not coming out. It's a one-way trip, okay?

NEIL DEGRASSE TYSON: So you don't just die because you disappear, you die long before you disappear. As you fall in, the gravity at your feet becomes rapidly greater than the gravity at your head, so your feet start falling faster than your head does. That's a bad situation to be in. You don't really—initially, you kind of feel good, you know? Because it's—we all stretch when you wake up in the morning. Initially, it feels like a stretch, but what happens is that stretch continues beyond comfort levels, and you reach a point where—and they're called the tidal forces, tides on your body basically. The tidal force becomes so great that they exceed the intermolecular forces that bind your flesh. And so the point comes where you snap into two pieces, likely to happen at the base of your spine. Now you are two pieces.

NEIL DEGRASSE TYSON: Now I know you didn't ask about this, but it turns out you will survive that snap because below your waist, while there are important organs, there are no vital organs below your waist. So your torso will stay alive for a little while, okay? Until you bleed to death, but this all happens much faster than it would take to bleed to death. So these two pieces then feel tidal forces, and then they snap into two pieces. And then they snap again into eight, and then 16, and then you're bifurcating your way down. And so eventually, it's your head and multiple other parts. And so that will continue until you are a stream of atoms descending toward the abyss. And it turns out that's not the worst of it, okay? The worst—it turns out the fabric of space and time funnels down towards a black hole, so the space that you occupy up here is larger than the space you occupy down here. So in fact, you're getting—while you're getting stretched, you're getting squeezed, extruded through the fabric of space like toothpaste through a tube.

JAD: Well, we're about to ...

ROBERT: Fall away, I think.

JAD: Oh, good! Nice one. Nice one, Krulwich. Before we do though, know that we have a podcast, it's at Radiolab.org. I'm Jad Abumrad.

ROBERT: I'm Robert Krulwich.

JAD: Bye.

[JOAN MURRAY: This is Joan Murray. Radiolab is produced by Jad Abumrad and Tim Howard.]

[FREDERICK COOLIDGE: Their staff includes Ellen Horne, Soren Wheeler, Lulu Miller, Brenna Farrell, Pat Walters and Lynn Levy.]

[JOAN MURRAY: With help from Sharon Shattuck, Raymond Tungercar, Sam Rildman and Nicole Croy.]

[FREDERICK COOLIDGE: Special thanks to Ari Daniel Shapiro, Anne Huang, Emily Corwin, April Kinzer and the City Arts and Lectures in San Francisco. How's that, guys? This is Fred Coolidge, all about the hypnic jerk. Bye.]

-30-

 

Copyright © 2024 New York Public Radio. All rights reserved. Visit our website terms of use at www.wnyc.org for further information.

 

New York Public Radio transcripts are created on a rush deadline, often by contractors. This text may not be in its final form and may be updated or revised in the future. Accuracy and availability may vary. The authoritative record of programming is the audio record.