General Question

AstroChuck's avatar

What is the purpose of a yawn?

Asked by AstroChuck (37278points) November 13th, 2009

I know when one is tired or bored a yawn is usually coming, but why? Is there some medical purpose here? And what makes them so damn contagious?
Just curious.

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33 Answers

drdoombot's avatar

I think it’s caused by low oxygen levels. A yawn forces you to take a deep breath.

reacting_acid's avatar

To torment everyone around you.

mangeons's avatar

I think that it’s because of low oxygen levels in your brain, and your brain is sending frantic messages to your lungs to get more oxygen in, and that causes you to yawn to get a large amount of oxygen, which is often why you yawn a lot while singing, making a speech, etc, because of the large amount of oxygen you put out while doing those types of activities.

eponymoushipster's avatar

To let the guy speaking know to wrap it up.

nebule's avatar

to secretly drink in all the dreams

arnbev959's avatar

Damn you, AstroChuck! You just made me yawn!

(And I think my oxygen levels were fine a moment ago, too.)

Foolaholic's avatar

I once had a critical reading section on the SATs that talked about all these studies they did to find the purpose of yawns, but never found any definitive results. But I agree with @drdoombot about low oxygen levels. I used to always find myself yawning after choral practice because I was exerting my breathing that much more, therefore using up more oxygen.

mangeons's avatar

@Foolaholic sniff what about me? :(

Foolaholic's avatar


Everybody lurves you anyway, but @drdoombot said it first.

applesaucemanny's avatar

my anatomy teacher said it’s usually just because you’re either tired or nervous, he’s a pretty reliable source

timtrueman's avatar

I’ve heard that it’s because your brain is too hot but I have no data or source to back that up…

Foolaholic's avatar


That’s interesting. I wonder what the significance of stretching one’s eardrums is; I can assume its like tuning a regular drum, but I wasn’t aware that your eardrums could be out of tune.

noelasun's avatar

I’m no longer confident about this, (after the wiki article had no mention) But last I read yawning was a mechanism that happened as our bodies transitioned into another state. ie. sleepiness to alertness, before presenting a speech, or as wiki shared, paratroopers before the jumped out of a plane.

AstroChuck's avatar

Now be honest. How many of you yawned at some point while reading this thread?

dpworkin's avatar

No one yet knows, but in just the last month I have heard two relatively new theories: One is that it is to equalize pressure in the Eustachian tube; one is that it is to cool the brain. It is no longer thought by most behavioral psychologists that it is an indicator of boredom or sleepiness.

Perhaps the most interesting question about the yawn is that yawns are contagious, which suggests that perhaps it once had a social function.

mangeons's avatar

I actually didn’t. /disappointed

nxknxk's avatar

What @pdworkin said. The last bit is what I’ve heard most about. It’s so interesting.

PretentiousArtist's avatar

To give you something to do when you’re listening to the Beatles

AstroChuck's avatar

Oh, F.U.! I will not tolerate blasfamy on any thread of mine!

Harrow185's avatar

Low oxygen levels, or when your brain needs oxygen

dpworkin's avatar

Uh, nope.

Harrow185's avatar

Then what is it ..

dpworkin's avatar

No one know yet. It says just that above if you would care to scroll up. There are some theories, there is no proof. We do know that it has nothing to do with oxygen levels in the brain. Those studies have been done and they were conclusive.

Harrow185's avatar

Terribly sorry, I forgot to scroll up. It was a opinion, I’m not looking for the best answer award. I went on a limb and guessed.

Resistka's avatar

Well when a common Adult Figure such as The parent, The Teacher, The Dramatic friends mom, The cop, The preacher, The Groomer, Ect. decide, “Hey, I’m gonna ask :NAME: a question” The annoyed Teen gets a drowsy feeling, breaths in, and exhales out, only to open their mouth big and wide, this tell’s the “Adult figure” To take a hike.

Resistka's avatar

Groomers annoy me, they… the ones ive met, are Smug… for no reason

Foolaholic's avatar


Sorry, the term “groomer” just makes me think of, like, animal groomers or something. I assume you mean more along the lines of barbers and such.

kitiara's avatar

…yawned all the way though reading other posts.. now need a lie down…thanks Astrochuck lol

JessicaisinLove's avatar

@ AstroChuck…..I did a few times. Thanks so much lol

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