Why do we yawn?

Ever wonder why you yawn when you’re sleepy or bored? Scientists want to know, too. (Yes, even scientists yawn.) But they just haven’t come up with a definitive answer yet.

The latest research points to yawning as a way to regulate brain temperature. A study published in Evolutionary Psychology found that yawning — the involuntary jaw stretch, mouth open with a deep inhale sometimes accompanied by a yowling groan — may be akin to how a radiator cools your car.

Why Do We Yawn?
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“On average, we yawn about eight times a day,” says study author Gordon G. Gallup Jr., psychology professor at the State University of New York at Albany.

The study asked participants to hold hot or cold packs to their foreheads and watch video of others yawning. Those that held the warm packs yawned 41 percent of the time, while people who held cold packs yawned just 9 percent of the time.

Yawning, the study purports, may be cooling your jets when you’re warm.

Hey dreamy, Your brain is hot

It seems the brain heats up more than other organs, and a yawn sends a big gulp of cooler air through the nasal and oral cavities — increasing the rate of blood flow to the skull and changing the temperature of the blood flow that cools off the brain.

In research of the thermoregulatory theory of yawning by Andrew C. Gallup, PhD, and Omar T. Eldakar, it is shown that an increase in brain temperature precedes yawning, which may explain why we yawn at night before we fall asleep and again in the morning when we wake up — both are times when body temperature reaches its peak.

What’s more, the reason you feel better after a hearty yawn may be because your brain functions better when it’s cooler.

Hot vs. cold climate

You also may find yourself yawning more in colder climates rather than warm ones. A report for WebMD conducted by Gallup says that colder outside air makes you yawn more frequently than warm or hot outside air.

To test the theory, researchers went to Tucson, Arizona in winter — temperature 71.6 degrees Fahrenheit outside — and then again in summer — temperature 98.6 degrees Fahrenheit. They asked 80 pedestrians to look at pictures of people yawning.

In the cooler weather, 45 percent of people yawned when they looked at the photos. But in hot conditions, only 24 percent did.

The collective yawn

As for why yawning seems contagious, researchers speculate that mimicking empathy may be behind catching someone else’s yawn, which 60 to 70 percent of people do, according to Gallup.

In the same way you smile in reaction to another person’s smile, or frown when someone frowns at you, the yawning response is likely an evolutionary byproduct of how our brains work. So if you find yourself yawning when others do so, (or right now as you read this) you likely have a large capacity for feeling their pain.

You can also yawn too much. Excessive yawning can be related to daytime sleepiness as well as brain issues, like tumor, epilepsy, multiple sclerosis or, more rarely, a problem with the body’s temperature control or a reaction to medication.

The Reason We Yawn
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Dissension among the yawning ranks

Some yawn theorists don’t buy the idea of temperature regulation as a trigger for yawning. These scientists think that sweating is enough of a cooling mechanism, therefore why would we need to yawn to cool our brains further?

This camp thinks yawning is more of a social effect, an unconscious behavior that communicates our empathy. Since the yawn is associated with being tired or bored, it communicates a sort of unpleasant emotion in the way a frown or grimace does.

Just in case they’re right, you might want to stifle your yawn at the morning meeting or while talking with your mother, so as not to give too much away.

Yawning is still a mystery, but recent research shows are closer to getting the answer. Now, time for a nap.

Written by Jennifer Nelson

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