Everybody knows that yawning is way to encourage a tired body to wind down for the day. But what is yawning, exactly? And why do we do it when we’re tired? In the latest health breakthrough, U.S. researchers have determined that yawning may be a natural way of regulating your brain temperature.
The researchers conducted a study that examined the frequency of yawns among 80 people in the winter and another 80 people in the summer. After being shown pictures of other people yawning, nearly half of the participants yawned while outdoors in winter, compared with less than one-quarter while outdoors in summer.
So why the seasonal variation? The researchers suggest that yawning is triggered by increases in your brain temperature, and that the physiological act of yawning is a way to promote brain cooling. Yawning helps cool your brain by forcing you to breathe deeply and by increasing blood flow to the brain through the act of stretching your jaw. The researchers have hypothesized that there may actually be an optimum temperature range in which you could expect to have the highest rates of yawning. So, when the air outside is cooler than your brain temperature, as in wintertime, yawning brings in some of the cooler air to regulate the brain’s temperature.
Another theory about why we yawn is to bring more oxygen into our bodies. When you yawn, you fill your lungs with oxygen and remove a build-up of carbon dioxide. This might explain why we tend to yawn more in the company of others. Larger groups of people produce more carbon dioxide, which means you need more oxygen to compensate.
Whatever the answer is to the mystery of yawing, there are a couple of medical conditions that are sometimes associated with yawning. Too much yawning could signal a heart problem or a health condition associated with excessive fatigue.