WebMD 1:01: Why Do We Yawn?

So this is what I had for lunch on Tuesday. Or was it dinner Wednesday?

[YAWNING]

OK. You know, the old paranoid me would think that I was boring you, causing you to yawn.

The old you is wise.

Ah, but the new, wiser me is up on all the latest yawning research. And a new study shows that yawning might be the body's way of cooling the brain.

Really? Please elaborate.

Your brain is always working. It guzzles as much energy as leg muscles would during a marathon. And it can burn up to one fifth of the calories used in a day, which is enough to power a 20-watt light bulb.

I get it now. Burning up all that energy heats up the brain. Then a yawn forms tiny ice crystals to cool it off So obvious.

Well, that's not ex-- exactly that, or even close. OK, so a yawn is a cool-down, yes.

But it works because stretching the jaw increases circulation. And that pumps warm blood out of the brain, while inhaling deeply brings fresh air into your system, giving you a nice, refreshing physiological brain chill.

Well, that definitively explains why we yawn.

Ah, actually, researchers are still working to find a conclusion everyone can agree on.

And there are a bunch of other theories out there, too, even one that links yawning to arousal.

So when you yawn around me, are you trying to ask me out?

What? No, not that kind of arousal, no. Maybe. If--

This just got weird. [BELL RINGING] [MUSIC PLAYING]