What a Yawn!

You might even find yourself doing it while you read this article.

From fish and birds to reptiles and mammals, nearly all vertebrates yawn. Even before babies take their first breath, they yawn in the womb.

Charles Darwin noticed the ubiquity of yawns, writing in his 1838 field notes, “Seeing a dog and horse and man yawn, makes me feel how much all animals are built on one structure.”

Darwin believed yawning was the effect of animals evolving from a common ancestor over a long period of time. But what Darwin was really observing was evidence of a common Designer.

Even though we know surprisingly little else about this familiar action, we can be certain of where yawns came from: the Creator God, who made everything during the six-day creation week.

Bring It Yawn

Yawning helps cool your brain by forcing warm blood out of your head and cooling down the blood near your lungs. The cool blood is then sent to your head.

You probably know that you yawn when you’re tired or bored. But yawns often occur after we wake up or right before we go to sleep. For a while, scientists believed that yawning might help rouse us by activating our brains and increasing our heart rates.

Today, however, the most widely accepted theory is that we yawn to cool our brains. A 2014 study published in Physiology and Behavior found that yawning occurred less in winter than summer.1 Another study conducted by Andrew Gallup, a psychology professor who researches yawns, found that people yawned less frequently while holding cold compresses to their foreheads.2

How does yawning cool the brain? Opening your jaw at the beginning of a yawn forces the warm blood in your brain to rush through blood vessels that move blood away from your head. At the same time, the air you’ve inhaled cools down the blood near your lungs. The cool blood is then sent up to your head.

If yawning is about cooling, why do we do it more in the morning or late at night? In the evening, your brain and body temperatures are at their highest point throughout the day. As you fall asleep, your body temperature drops rapidly to prepare for sleep. When you wake up in the morning, your body and brain temperatures rapidly increase. Yawning is thought to help facilitate these changes.

Pass It Yawn

What about pass-it-on yawns, when seeing, hearing, or thinking about yawning increases the likelihood that you’ll do it too?

Many scientists believe we catch yawns from those we love because we share an empathic connection with them. Past studies have shown that those who score higher on empathy tests are more susceptible to contagious yawning.

But more recent studies indicate that the empathy theory might not be true. Now, scientists believe seeing a yawn activates your mirror neurons, causing you to unconsciously copy the behavior. We mirror other behaviors, too—smiling back at someone who has grinned at us, crossing our legs after watching someone else do it, feeling an itch after seeing someone scratch their arm.

It’s still true that you’re more likely to yawn after a friend yawns than a stranger, but according to Gallup, that may simply be because you’re more likely to look at the people you love. Catch a stranger’s eye, and you might also catch their yawn.

Let It Out

Yawns are perceived as rude because they convey sleepiness or boredom. Should you stifle your yawns during an important meeting or lecture? In 2009, one judge certainly thought so. He sentenced a spectator to six months in jail for contempt of court after the man yawned during a court session.4

Contrary to popular belief, yawning—and the subsequent cooling of your brain—might actually make you more alert and improve your attentiveness. The next time you feel yourself getting sleepy during a meeting, don’t stifle that yawn—let it out!