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Why do we yawn?
July 3, 2007 6:31 AM   Subscribe

Why do we yawn? There are many theories. New research suggests it cools the brain.. a cooler brain is more alert.
posted by stbalbach (42 comments total) 4 users marked this as a favorite

 
ennui
posted by fydfyd at 6:46 AM on July 3, 2007 [2 favorites]


I yawned just reading the question "Why do we yawn?".
posted by Dr-Baa at 6:56 AM on July 3, 2007 [1 favorite]


Dammit. I attempted to read some of the links and yawned no less than five times. I need to get out of this thread- my eyes are starting to water.
posted by Dr-Baa at 6:58 AM on July 3, 2007 [1 favorite]


I just yawned reading Dr-Baa's comment about the question "Why do we yawn".

And again typing that.
posted by gomichild at 6:59 AM on July 3, 2007


Do you reckon that it might be a form a coercion/control, in that we show our teeth and that's threatening. I'm tired - I display threatening behaviour (show my teeth with a wide open mouth), you'd better follow suit (you comply rather than challenge).
posted by tellurian at 7:00 AM on July 3, 2007


But it's the many theories phenomenon that heats up the brain in the first place.
posted by weapons-grade pandemonium at 7:04 AM on July 3, 2007 [1 favorite]


Constable Detritus, reporting for duty...
posted by pupdog at 7:05 AM on July 3, 2007 [3 favorites]


Newborns have problems with heat-retention and in particular their heads have a high (compared to older children and adults) surface-area to volume ratio, making the problem even worse for their brains. Newborns yawn. I doubt it's to cool their brains.
posted by DU at 7:07 AM on July 3, 2007


Stop saying that word.
posted by lalochezia at 7:10 AM on July 3, 2007


Do you reckon that it might be a form a coercion/control, in that we show our teeth and that's threatening. I'm tired - I display threatening behaviour (show my teeth with a wide open mouth), you'd better follow suit (you comply rather than challenge).

I know nothing about...whatever kind of behavioral science would study this kind of thing, but I tend to doubt it. Why would everyone comply? If it's instinctual, than wouldn't some people challenge?
posted by dismas at 7:12 AM on July 3, 2007


I don't buy this. How much cooling is achieved with one yawn? How long would such cooling effects last? Why would yawning be associated with tiredness and boredom and not, say, hiking in the desert?
posted by effwerd at 7:16 AM on July 3, 2007


No, no, no. It is to embiggen the jawbitering bands. Yeah, that's the ticket.
posted by Henry C. Mabuse at 7:20 AM on July 3, 2007


God damnit, I can't read about yawns withaaaoot goOOOOAAAAAAAUUHHHHHHH
posted by tehloki at 7:20 AM on July 3, 2007 [2 favorites]


If yawning cools our brains, then why are yawns contagious? Are our brains jealous of other "cooler" lobes? Is there some sort of cliquish nature to brains? It's hard to tell...my brain just told me 'yes.' Now it's telling me to go get some cookies. Be right back...
posted by NationalKato at 7:21 AM on July 3, 2007


The question isn't "Why do we yawn" but "why do animals yawn" Since we evolved from animals, Yawning may have served some purpose in pre-human animals that may be vestigial today.

I think it's just a way for animals to signal their sleepiness to each other in order to get groups to go to sleep at the same time.
posted by delmoi at 7:23 AM on July 3, 2007 [1 favorite]


Another good sleep signal: Lying down, closing your eyes and going "honk-shuuuuuu".
posted by DU at 7:29 AM on July 3, 2007 [2 favorites]


What is most interesting about this question is how many people think they know the answer. In fifth grade science, I was taught that people yawn because they need more oxygen at that particular moment. It was fact. It wasn't until much later, when I was an adult, that I learned that nobody really knows. I guess that was true of many things.

Science is much more interesting when you realize how many unanswered questions there are.
posted by jiiota at 7:31 AM on July 3, 2007


I think it's just a way for animals to signal their sleepiness to each other in order to get groups to go to sleep at the same time.

Or to look completely adorable

it is more difficult to find cute animals through GIS than I had anticipated
posted by dismas at 7:37 AM on July 3, 2007


a cooler brain is more alert

Is this true? Are people more alert when living in cold climates than in hot climates? Is there an optimum operating temperature, or does it just depend on what you're used to?
posted by hoverboards don't work on water at 7:37 AM on July 3, 2007


I yawn to show the world how much oxygen I can take in all it once, hoping they will be impressed. But they all immediately respond by demonstrating that they are also capable of taking in large amount of oxygen in one large gulp, thereby shaming me.
posted by Astro Zombie at 7:38 AM on July 3, 2007


a cooler brain is more alert.

Is this why the South votes Republican?
posted by uosuaq at 7:51 AM on July 3, 2007 [2 favorites]


Yaaaawwwwwwwn.
posted by Pope Guilty at 7:58 AM on July 3, 2007


Also, a present for the text-to-image crowd.

http://thefuntimesguide.com/images/blogs/yawning-man.jpg
posted by Pope Guilty at 8:00 AM on July 3, 2007


Is this why the South votes Republican?

No, we vote Republican because we are against the socialist agenda of the Democratic Party.

Thought you guys would have picked up on that by now.
posted by tadellin at 8:01 AM on July 3, 2007


No, we vote Republican because we are against the socialist agenda of the Democratic Party.

I was right, you are some kind of performance artists.
posted by Pope Guilty at 8:05 AM on July 3, 2007 [1 favorite]


Why do we yawn?

Because we're fucking tired? I win.
posted by phaedon at 8:18 AM on July 3, 2007


Just we need. A behavioural recipe for more cool brains. I can already picture the avalanche of 'meh' comments this will result in.
posted by srboisvert at 8:35 AM on July 3, 2007


Is this why the South votes Republican?

Haha
posted by spotty_dog at 8:38 AM on July 3, 2007


What do we know about the function of a yawn? It equalizes the air pressure in the ear canals by opening up the eustachian tubes. I think you could develop yet another theory from that starting point.
posted by kozad at 9:09 AM on July 3, 2007


Southerners do have a reputation for being hot headed.
posted by stbalbach at 9:31 AM on July 3, 2007


i like the idea that we show our teeth automatically when tired to warn competitors away from mates / food, so that they won't think we are incapacitated by tiredness and strike.

and of course the learned social behavior of covering up our mouths when yawning would be to hide that aggression as it's not polite (or veil it slightly, as the article notes).

great post.
posted by luriete at 9:42 AM on July 3, 2007


If yawning serves the purpose of getting everyone to sleep at the same time, why would solitary animals yawn, e.g. wild cats.
posted by JeNeSaisQuoi at 10:03 AM on July 3, 2007


Damnit I yawned something like eight times reading this... nine times reading this thread.

Damnit, TEN. I'm leaving.

Why do we yawn just thinking about yawns (eleven) or when we see the word?
posted by CitrusFreak12 at 10:06 AM on July 3, 2007


It also feels good, like stretching or sneezing.
posted by Atom Eyes at 10:20 AM on July 3, 2007


Previously.

My money's still on satanic possession.
posted by inoculatedcities at 11:50 AM on July 3, 2007


Wow, clicking on the "yawn" tag there is a whole history of yawn posts, who knew. MeFi is becoming a database of.. something.
posted by stbalbach at 11:59 AM on July 3, 2007


And stupid ol' me was thinking that it was the increased oxygen that gets into the bloodstream that brings about a brief period of increased lucidity when we're tired.
posted by porpoise at 2:06 PM on July 3, 2007


The best-sounding theory I've heard was published a few years ago. Yawning isn't about oxygen, or brain-cooling, or anything else. It's about focusing your attention. If you're sleepy, yawning will tell you that you need to sleep. It's not that you're tired per se, but that sleep is a priority. It's like a gentle slap in the face. The intersting thing is how it's contagious. This goes back to our evolutionary beginnings. We yawn when we see others yawn so that the group (tribe) can be a cohesive unit, therefore a strong unit against sabertooth cats and such. Everyone in the group gets that gentle slap and ends up on the same page.

Makes sense to me, anyway. I wonder if yawning is contagious with other animals.
posted by zardoz at 6:01 PM on July 3, 2007


"and of course the learned social behavior of covering up our mouths when yawning would be to hide that aggression as it's not polite"

I dunno about you, but I cover my mouth when I yawn to avoid spraying saliva all over the place. It doesn't happen that often, but when it does it's like a (very small) squirtgun.

Does this not happen to normal people?

I don't think there's anything to do with warning others away, anyway. It certainly doesn't do you any favours in the "showing you're not incapacitated" dept; if anything it advertises that you soon might be, while at the same time making you an easier target during the yawn.

I don't much buy the oxygen/deep breathing thing either -- I rarely take much of a breath during a yawn, I just stretch my jaw while making a slow shallow exhale; maybe it's bigger than it feels, but why the stretching? I think it's probably more to do with redistributing fluids, and helping to keep a full range of motion in the jaw, perhaps with some minor communicative advantages.
posted by Freaky at 7:03 PM on July 3, 2007


I have a strange personal anecdote about yawning. Or, rather, not. Once upon a time I lost the ability to yawn for about three hours. The circumstances that led to this were debauched, but there was no obvious thing that should have caused it. However, it was on the late side of the evening, and I was not able to yawn for a significant length of time. But I wanted to.

The desire grew into a stronger and stronger need, and eventually rose to the level of discomfort. I was sitting in a relaxed position, and yet experiencing something akin to a shortness of breath. It felt as if I was not able to circulate the entirety of the air out of my lungs. As if the bottom part of the lungs was filled with stale air that needed to be cycled out with a good yawn, but couldn't be. As a result, I was not able to breathe in fully either.

The ending to this story is exceedingly undramatic, and it is rather difficult to gussy it up in any way. Eventualy, with massive relief, I yawned. Successfully.

I conclude, therefore, that at least one significant purpose of yawning is fully to clear out the lungs and take in new oxygen. Perhaps when we are tired our lungs begin to go to sleep a little bit before the rest of the body. During sleep, breathing often slows, and it begins to slow as we tire. However, if we are still active, better air circulation is needed and therefore we yawn.

The latter half of this is speculation. I am only guessing at why there arises, especially towards the evening, a need for an additional method to expel air from the farthest reaches of the lungs. But I know from this admittedly bizzare experience that a vigorous recycling of air in the lungs is an important purpose that is served by the need to yawn.
posted by yoz420 at 7:10 PM on July 3, 2007


It also feels good, like stretching or sneezing.

Atom Eyes beat me to it, though I was intending to use the somewhat more vulgar examples of knuckle cracking and masturbation...

Obviously we yawn because it feels good. Why yawning should feel good is a deeper question, for which I don't have a good answer.
posted by Tube at 7:18 PM on July 3, 2007


kozad reminds me that in an earlier yawning thread I wrote:
Actually, yawning is contagious because when one person yawns it equalizes the head pressure but therefore slightly changes the pressure outside the head so now everyone else has to yawn to re-equalize their own pressure in the head to the new outside pressure. That is why yawning is contagious.
Amazingly, someone felt the need to inform me that this explanation is not accurate. Humor no translate well to internet, or perhaps it just wasn't funny anyway.
*yawn*
posted by zoinks at 2:13 AM on July 5, 2007


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