Why do we yawn?

Most of us associate yawning with being bored, tired or even hungry. However, there has been no clear scientific evidence to support these claims. There has not even been any clear explanation as to why a person yawns when yawning is seen from another person or when the topic is read or even just thought of.

As we may all know, yawning is that experience when we open our mouths wide, allowing the inhalation of more air and then followed by an exhalation. This behavior is something involuntary, which means that we have no control as to when and where we yawn ‚ it is even hard to suppress yawning.

Yawning may have been associated with boredom because during these moments, we tend to have shallow breathing ‚ thus less oxygen is carried into our lungs. Yawning occurs when this happens or when we experience fatigue, in order to let more air into the lungs. During moments that we do not use our lungs full capacity, as in the times that we are breathing at rest, the air sacs inside the lungs would collapse and the lungs stiffen up a little bit because they do not get fresh air. Thus, it is a body reflex that we yawn or sigh so that more oxygen can go in.

After we do this involuntary behavior, it is normal to feel more alert since the oxygen intake causes or heart rate to increase a little. Inhaling oxygen during yawning helps in forcing more of it into the blood and in getting rid carbon dioxide out of the blood vessels and the lungs.
It is still a mystery though as to why a person yawns after seeing another person do it or even just after reading about the topic. It is even a greater mystery why fetuses would yawn in the womb when, in fact, they do not need oxygen into their lungs until after birth.