Photo of a woman yawning
Scientists say yawning has role to play in keping the brain cool

Go ahead an yawn – it’s good for your brain

30 November, 2011

Natural Health News — If you feel like yawning, go ahead!

Though it’s often considered a mark of boredom or fatigue, yawning might also mean you are hot-headed. Literally.

In the current edition of the journal Medical Hypotheses, Andrew Gallup of Princeton University and Gary Hack of the University of Maryland argue that yawning helps to regulate the brain’s temperature.

“The brain is exquisitely sensitive to temperature changes and therefore must be protected from overheating,” they write. “Brains, like computers, operate best when they are cool.”

In another study earlier this year, published in Frontiers in Evolutionary Neuroscience, the same scientists found that yawning frequency varies with the season and that people are less likely to yawn when the heat outdoors exceeds body temperature.

Many animals, including humans, yawn and the action of yawning is involuntary. Despite numerous theories posited in the past few decades, very little experimental research has been done to uncover the biological function of yawning, and there is still no consensus about its purpose among the dozen or so researchers studying the topic today.

For instance, yawning has nothing to do with increasing the body’s oxygen supply. In experiments, people yawn just as much in oxygen-rich air as they do in an oxygen-poor atmosphere.

“Enter the brain cooling, or thermoregulatory, hypothesis, which proposes that yawning is triggered by increases in brain temperature, and that the physiological consequences of a yawn act to promote brain cooling,” says Gallup

According t his theory, the walls of the human maxillary sinus, flex during yawning like a bellows.

The cooling effect of yawning is thought to result from enhanced blood flow to the brain caused by stretching of the jaw, as well as counter-current heat exchange with the ambient air that accompanies the deep inhalation.

The theory helps explain not only the utility of yawning, but also the function of the human sinuses, which is, amazingly, still poorly understood and hotly debated.