I've always thought that yawning is caused by lack of sleep, which is not true.
Recent studies indicate that yawning is a good thing, because it cools the brain and increases our alertness.
The next time you are caught yawning in from of your boss or in meetings, you can tell them that yawning is a physiological mechanism designed to maintain attention. So, it is a compliment to their speech, just like clapping hands.... hahahaha...
More about the yawning research:
According to psychologists Andrew Gallup and Gordon Gallup of the State University of New York at Albany, we do not yawn because we are sleepy, bored, or need oxygen. Yawning is simply a brain-cooling mechanism. Yawning enhances the brain’s functioning by increasing blood flow and drawing in cooler air.
Not only that, brain-cooling explains why you can "catch" a yawn, says Gordon Gallup. "We think contagious yawning is triggered by empathic mechanisms which function to maintain group vigilance." In other words, yawn-catching evolved to help raise the attentiveness of the whole group.
The brain burns up to a third of the calories we consume, and as a consequence generates heat. The research volunteers were asked to watch a video showing people behaving differently (neutrally, laughing or yawning) while inhaling and exhaling in one of four ways: strictly orally; strictly nasally; orally while wearing a nose plug; or to just breathe normally. Researchers found that 50 percent of the people who were instructed to breathe normally or through their mouths yawned while watching other people yawn, while those told to breathe through their nose did not yawn at all.
In another experiment they found that subjects, who held a cold pack to their forehead or who were instructed to breathe through their nose, did not yawn, while those who held a warm pack or a room temperature pack to their forehead yawned normally.
Evidence shows that blood vessels in the nasal cavity and face send cool blood to the brain, and by breathing through the nose or by cooling the forehead, the brain is cooled, eliminating the need to yawn.
The New York Times