Yawning is an unconditioned reflex, such as sneezing. There are several hypotheses about the causes of yawning that are not entirely proven. Some believe that we yawn to quickly oxygenate the blood when we are tired, others think that this is how we cool our brain, and sometimes relieve nasal congestion during illness / pressure drop. Recent studies (links to which, alas, I cannot give) tingle that yawning is a manifestation of sympathy / affection for a person. Every theory, when examined, seems to be correct.
I cannot say for sure, but in my opinion and my own observations, a person yawns when breathing is complicated by something, that is, a person needs more oxygen in less time, but a person cannot get this amount by simply inhaling and exhaling , then the body resorts to yawning to inhale as much oxygen as possible
Two main hypotheses are that either yawning helps to enrich the lungs with oxygen, or that it cools the brain. It has been shown that overheating of the brain impairs reflexes, coordination and reaction, etc., so this is a kind of protective function. Read more here.
maybe I'm not really talking about this right now, but at school a chemistry teacher told one of the theories on why one person's yawn causes a chain reaction among others. in general, the fact is that when we see a yawning person, our brain reacts like this: “oh! it is stocked with oxygen! what if I don't have enough - I should also stock up ... "
I don't know if it's true, but from her lips it sounded pretty convincing :)
We yawn because we do not have enough oxygen to feed our cells, and in order to replenish the supply of oxygen in the blood, our body forcibly "captures" air bypassing our will, moreover, as it needs - a wide, deep breath that fills the lungs completely .
This is unknown to science. There are several assumptions of varying degrees of probability, but none of them has been proven one hundred percent. The most widespread and probably correct theory is that yawning is an effective means of improving blood flow to the brain. The fact is that when a person tends to sleep, his strength and the speed of all processes occurring in the body, including blood supply, decrease. Yawning is a way to stimulate him. We also yawn with boredom. Why? I have spent many years studying this issue, but I have no clear explanation. Perhaps monotony also leads to a deterioration in blood supply. But this is just a guess. Unfortunately, on the issue of yawning, we are still flying a white flag.
What pushes them to do this? After all, even running 42 kilometers is very difficult. And some run 70, 100, 160 km. Or even whole days and weeks