December 15, 2008

The Yawn Explained

I've wondered about this all my life.  Why do we yawn? 

Now, the Discovery channels claims to answer that question. It Cools Your Brain

If your head is overheated, there's a good chance you'll yawn soon, according to a new study that found the primary purpose of yawning is to control brain temperature.
The finding solves several mysteries about yawning, such as why it's most commonly done just before and after sleeping, why certain diseases lead to excessive yawning, and why breathing through the nose and cooling off the forehead often stop yawning.
The key yawn instigator appears to be brain temperature.
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The new findings also explain why tired individuals often yawn, since both exhaustion and sleep deprivation have been shown to increase deep brain temperatures, again prompting a yawn-driven cool down. Yawning additionally appears to facilitate transitional states of the brain, such as going from sleep to waking periods.
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"Bouts of excessive yawning often precede the onset of seizures in epileptic patients, and predict the onset of headaches in people who suffer from migraines," he added.

Now  I recall when I used to suffer from migraines, I yawned a lot.

But Discovery solved the puzzle of why yawning is so contagious

 Yawning, Contagious

photomontage by Zachary Scott

Some  contend it's the capacity for empathy, but why do we yawn just thinking about it?

Steve Platek, a cognitive neuroscientist at Drexel University is the go-to expert.

Platek says he thinks it has to do with empathy. The way he sees it, the more empathetic you are, the more likely it is that you'll identify with a yawner and experience a yawn yourself. In a recent study, Platek looked at contagious yawning in people with "high empathy," "low empathy" and everything in between. He found that higher empathy meant more yawn-susceptible and lower empathy meant more yawn-immune.

But that wasn't proof enough. So Platek put volunteers in M.R.I. machines and made them yawn again and again to pinpoint the areas of the brain involved. When their brains lighted up in the exact regions of the brain involved in empathy, Platek remembers thinking, "Wow, this is so cool!"

Some yawning researchers - of which there are few - have identified many types of yawns. There's the contagious yawn, the I'm-tired yawn and the I-just-woke-up yawn. There's the threat yawn, which is the my-teeth-are-bigger-than-yours yawn that's so popular with primates. ("People do it, too," says Platek, "but unfortunately, we don't have scary teeth anymore.") There's also the sexual yawn. (One scientist claims that yawns are used in seduction.)

At some point, you have to wonder: why study yawning? It's quirky, interesting, but not important, right? Wrong, says Platek. Nearly every species on the planet yawns: insects, fish, birds, reptiles, mammals. "Yawning is such a primitive neurological function," Platek says, "it's a window into what happened during the evolution of the brain."

The good thing about yawning is that it's not boring. "Scientists like me usually go to conferences and give talks about technical mumbo jumbo," Platek says. "The audience always yawns, and we're up there thinking, Oh, man, they're so bored! But when I give a talk about yawning and they yawn, I think: Sweet! They're paying attention!"

Posted by Jill Fallon at December 15, 2008 10:52 PM | Permalink