From the brains behind brains on, this is the Moment of Um.

Um, um, um, um, um, um, um, um, um, um, moment of um comes to you from APM Studios. I'm Ruby Guthrie.

Um.

It's a rainy Saturday afternoon. You're in the coziest spot on the coziest couch in your

house. You have the softest blankie curled up all around you, and you're at a really, really good

part in your book. You've been there for a few hours now. Where is the time gone? Now that you

think about it, wow, you're really thirsty. So you toss the blanket

off your lap, you lay your book down, and you put one foot on the ground and, ow, what is that

tingly sensation you're feeling on the bottom of your foot? It's like you're standing on pins and needles.

Oh no, your foot fell asleep. It's probably because you've

been sitting for so long. But what exactly is going on in your body? Listener Ethan was wondering

the same thing. Hi, my name is Ethan, and I'm from San Jose, California. And my question is, what happens when parts of your body fall asleep?

Hi, I'm Dr. Karen Litsy.

I'm a physical therapist based in New York City.

And the question is, what happens when a limb falls asleep?

So it might be your foot or your hand falls asleep and you get those pins and needles sensation

in your hands.

So when this happens, it's usually a lack of blood flow to a nerve.

So there's 45 miles of nerves in your body.

And your nerves need blood flow, space, and movement to function

properly. So, for example, if you're leaning on your elbow for a long time, your hand might fall

asleep because a nerve that runs down to your hand is pretty superficial or kind of up on the surface

...