Why do we yawn

Unfortunately, the topic of why do we yawn is much in debate and most theories, while convincing, are unproven. That means essentially, no-one knows why we yawn. It is widely believed that yawning occurs because we are tired, bored or see someone else doing it and despite it being quite a common occurrence in these situations there is still no evidence to suggest this is true. Although the exact mechanics of yawns are not known even to the most experienced scientists, they tend to all agree that yawning is an involuntary respiratory reflex that occurs in order to regulate the carbon dioxide and oxygen levels in the blood.

Technically speaking a yawn can be described as a reflex of the mouth followed by a deep inhalation and a slow exhalation of oxygen. However, this doesn’t help us much when we try to answer the question “why do we yawn?”
Scientists have also suggested that the rumor of yawning occurring when we are tired or bored may actually be true because at these times are breathing is shallow an oxygen supply is low. However, this has yet to be verified.

When an individual yawns, they become “energized” to their surroundings essentially becoming much more aware and alert. This is due to the sudden large intake of oxygen that the yawn produces which in turn leads to an increased heart rate, as well as flushes out the carbon monoxide build up and restores normal breathing and ventilation.
This would support the theory that yawning occurs when we are bored or tired as it can act as a kind of make shift boost to our system to keep us up that little bit longer. However, this fails to explain “why yawns are contagious” as the age old mystery of yawns still eludes us. No-one knows why yawning would seem to trigger other people’s yawns beyond a simple matter of the power of suggestion. In addition to this, it is also not known why patients with lower brainstem damage or MS (Multiple Sclerosis) seem to suffer from excessive yawning and what this means.

It may also interest you to learn that unborn fetuses also seem to yawn in the womb despite their supply of oxygen originating form the umbilical cord and not from breathing. Babies do not take in any oxygen into their lungs until they are born and breathe through their nose and mouth for the first time.
Funnily enough, some men also associate yawning with a penile erection. This is probably caused by the increase in oxygen flow through yawning that in turn increases the flow of blood that can cause an erection or partial erection. However, why yawning and penile erections seem to be associated is still unknown and largely a mystery.

It is also one theory however, that the sudden intake of oxygen is in fact designed to cool down the brain and help it work more efficiently. Once again however, this is all mere speculation as just one of a large variety of different theories on this topic.