Wake up! Here’s some important news about yawning
Yawn. Nice nap? After Thanksgiving dinner, I mean. This holiday got me to wondering about why we yawn.
And guess what? We don’t know. Yep, the whole yawning thing appears to be a big mystery to scientists.
Wow! How can we not know the reason for yawning? And people think science is boring.
So I decided to demonstrate just how daring a scientist can be and devote an entire column to yawning, in spite of the evidence that yawning is contagious. There is a huge risk of putting my readers to sleep by the end of the fourth paragraph. Live dangerously, I always say.
The study of yawning is called chasmology. (I’m not making this up.) A yawn is an ancient, stereotyped, involuntary reflex involving stretching the body.
There is the opening of the mouth wide, followed by a slow inspiration of air, stretching of the ear drums, expansion of the lungs, increased heart rate and the rapid exhalation of air. Reptiles, birds and mammals all yawn. (Yawn.)
There are a lot of theories about why we yawn, but most of them have larger chasms than the yawn itself.
For example, it is commonly thought that we yawn to get extra oxygen, perhaps because we haven’t been breathing deeply enough.
However, Robert Provine from the University of Maryland showed that neither increased oxygen nor decreased carbon dioxide altered the yawning rate. Actually, yawning slightly decreases blood oxygen.
Another theory is that yawning is some ancient, visual, communication system like smiling or frowning. (Are you still awake?) Maybe it was originally a polite way of saying “I’m tired. Go home now.”
I don’t think this is a very good explanation. It is hard to imagine why a reptile would need to yawn to tell the other snakes to go away.
Maybe we yawn to stretch our lungs. If they get a little wrinkled, like balloons that have become deflated, a yawn would stretch them out again. But why would you need to stretch out your lungs before going to sleep? And is there any evidence that lungs get wrinkled anyway?
A lot of people just think yawning means you are tired or bored. So why do people yawn early in athletic activity? Besides, I reject that theory because all those students in my class couldn’t possibly be that bored. (Yawn.) Besides, people yawn when they wake up, also. Are we bored of sleeping? In fact, some studies suggest that humans yawn more upon awaking than they do when somnolent. If morning yawning is to wake up, what is evening yawning for?
The most recent theory is that we yawn to cool our brains. Extended brain usage overheats the brain. When we draw fresh air in, it cools the blood and speeds circulation to the brain.
Gordon Gallup, a psychologist at University of Albany, did an experiment, in which he asked students to watch videos of people yawning. (By the way, are you still awake?)
If the students breathed through their mouths and held hot compresses to their head, they yawned more than if they breathed through their noses, a natural brain coolant activity, and held cool compresses to their foreheads. I’m pretty sure this theory isn’t true both because I yawn a lot, and my brains are not so hot.
One of the neat things about science is that when we discover that we don’t know something, it is very freeing. Because no one knows, we can imagine whatever we want until someone proves us wrong.
So here’s my theory: I think we yawn when we change states of activity. As we drift to somnolence, perhaps we yawn to step down the oxygen levels. Then as we awaken, we yawn to increase blood flow to muscle and brain. (Yawn.) I think that when ... (yawn) ... ever we ... (yawn) ...
Gary McCallister is professor of biology at Mesa State College. (Yawn.)