Gilbert K Chesterton once said ‘A yawn is a silent shout.’
Ever wondered why it is that we yawn at the end of a long, boring or a stressful day?
What happens inside our body when we yawn? Is there more to this seemingly insignificant trait shared by vertebrates? There are several theories regarding the mechanics of a yawn in the body by different fields of study.
Some neuroscientists claim that yawning is actually a cooling mechanism for our brain. Our brain is like a machine which is constantly employed by the body for making millions of decisions prompting survival. Like every other overworked machine, the brain has a tendency to heat up. The heat generated in the brain is actually comparable to that of any complex electric circuitry since the specialised cells in our brains (neurons) are interconnected to form a similar network.
The biochemical and metabolic processes occurring in these neurons generate heat, which subsequently raises the temperature in the brain. This rise in temperature triggers a physical process — yawning — to cool the brain and help resumption of efficient brain activity. Ultrasound studies illustrate that foetuses also yawn. It is speculated that yawning in foetuses is one of the means of brain development.
Often we feel refreshed post yawning or even alert. Why is that? Yawning is a brief involuntary process involving forceful wide opening (gaping) of the mouth accompanied by stretching of muscles in the mouth region and often, in other parts of the body.
Scientists speculate that yawning increases the intake of air (especially oxygen) which results in the heart pumping rich oxygen to various parts of the body. Pure oxygen is required by the cells in our body to function optimally. Apart from this, the least exercised muscles in your throat and your tongue are stretched while yawning.
So if you end up yawning in the middle of the day while working, that is just your body trying to stay alert.
The thing that strikes me the most about a yawn is that it is extremely contagious! I almost always find myself stifling a yawn whenever I see another person yawning. Don’t you? A few evolutionary biologists claim that yawning is actually a herd instinct whereby animals that are preyed upon tend to yawn contagiously so as to stay alert when a predator is on the prowl and also to synchronise their sleep patterns.
Yawning is considered a sign of empathy by psychologists, indicating that we tend to mimic yawning by other people to empathise with their state of mind or lethargy.
Yawning is indicative of several medical conditions; neurological intercranial hypertension, brain tumours, multiple sclerosis as well as other disorders such as diabetes are associated with excessive yawning.
However, excessive yawning is also a natural phenomenon observed at times of stress when the level of cortisol (stress hormone) is high in the body fluids. Yawning can be a warning signal or a sign of aggression. Darwin suggested via his book The Expression of the Emotions in Man and Animals that baboons attempt to threaten their enemies by displaying their teeth while yawning. A yawn can imply a threat and is used by primates to maintain and establish hierarchy in their social groups. Since several basic primate characteristics have become obsolete in humans, the act of yawning might have also lost its significance.
Despite the theories and studies, yawning is still a highly obscure action. So the next time you try to hold back a yawn, just remind yourself it is probably your body trying to refresh or recharge itself, so yawn away!