Yawning Helps to Regulate the Temperature of Your Brain
Yawning is not because you are tired, bored or need additional oxygen in your brain. And if you read that last sentence and yawned, it's not because yawning is contagious. There is now research suggesting that the reason why people yawn is because they are a "hot headed". No, not the type of "hot headed" that signifies that someone is short tempered and easily angered, but instead, someone that needs to cool their brain temperature.
In a theory proposed by Gary Hack of the University of Maryland School of Dentistry, Andrew Gallup of Princeton University and a group of researchers at the University of Vienna, yawning helps to regulate the brain's temperature by cooling it.
According to the journal Medical Hypothesis, Hack and Gallup write that the brain is "exquisitely sensitive to temperature changes and therefore must be protected from overheating." Hack and Gallup compare a brain to a computer and say that the brain will operate best when it's cool.
To further the study, researchers at the University of Vienna tracked the activity of their subjects and found that factors such as age, time spent outdoors, the season or even hours of sleep the night before did not have a significant effect on the frequency of someone yawning.
But one common factor stood out with all the test subjects: temperature. It was determined that the higher a temperature, the better chances of the subjects yawning. And if your body feels that a big intake of air will bring your brain temperature down, the yawning will begin.
So how does this work? Hack and Gallup believe that "the wall of the human maxillary sinus will flex during yawning, acting like bellows, which in turn facilitates brain cooling."