Yawning is very contagious, not only among humans but also among chimpanzees and dogs too. When you see a person yawn or simply talk or read about yawning, you cannot stop yourself from yawning. Normally we yawn when we relax, overwork and feel bored, tired or drowsy wanting to rest. It only signals our tiredness to the people around us. Let’s read about what happens when we yawn.
While we yawn, we actually take a deep breath. The respiratory system of the body is involved during yawning activity. It all starts with the mouth opening widely to take in lots of air, with the lungs expanding and then pushing out (exhaling) some of the air through the mouth.
From a behavioral study, yawning is found contagious because of the human capacity to recognize emotions that are being experienced by another person. Scientists have done researches to find out why we yawn. But they have not come up with a strong theory as yet. One of their popular reasons is that yawning helps to cool the brain. A cool brain in turns works very efficiently. Observing the circumstances in which people yawn, they find that people yawn in order to increase their state of alertness.
Yawning helps in alleviating the pressure on the ear drums while we travel by air. Yawning is not a disorder as long as it is not excessive. Yawning excessively is an act of yawning in very close succession (say many times in a minute). Excessive yawning could be the first sign of what is called vasovagal reaction. This is caused by the action of vagus nerve on the blood vessels. This in turn changes the blood pressure and rate at which heart works leading to heart disease.