From the brains behind brains on, this is the moment of um.

Moment of um.

Moment of um comes to you from APM Studios. I'm Rosie DuPont.

A mosquito bites you.

Your grandma knits you a scratchy blanket.

Your friend tickles you with a feathery cat toy.

You're posing for a family portrait and you're not supposed to move

but you have an itch on your ankle that you absolutely have to do something about.

What do all these scenarios have in common?

They're itchy.

Listener Samantha was wondering why we itch.

And someone better tell me soon because all these tickly situations

are driving me bananas.

What makes us itch?

I've always wondered the same thing and that's why I decided to study it.

Hi, my name is Sonale, Molly, and I study why the itch and what makes us itch and why sometimes an itch doesn't stop.

The kinds of things that can cause it can be chemicals that might be coming from

plants and insects. They can also be chemicals that are released by our immune cells to tell us to experience itch,

or they can be something like a light touch or an itchy sweater.

Itching is useful because our sensation of itch

serves as this really important warning system for us and it tells our

brain okay look there's something here that we don't want here and so we're going to do a

...