Yawning all the time, are you infected?

In the office, everyone was working quietly. Then, someone yawned, causing everyone to laugh. After the silence returned, people yawned one after another, and for a while, the office was filled with yawns. Yawning is not a virus, so why is it "contagious"?

Simple yawn, complex reasons

Yawning is a reflexive movement that many animals, including humans, perform. It involves opening the mouth to inhale, while stretching the muscles and tissues of the face. Although it seems simple, there are complex reasons behind it.

Generally speaking, we yawn when we are sleepy, tired, or bored. When the carbon dioxide content in a person's blood is relatively high, it is easier to yawn. Therefore, one possible explanation scientists have for yawning is that yawning causes a large amount of air to be inhaled, which can actively increase the efficiency of breathing and ventilation, just like deep breathing, making the mind clearer.

Other scientists believe that yawning helps control our body temperature, especially the temperature of the brain. In their tests, subjects with ice packs on their heads were less likely to yawn when they saw others yawn.

In addition, psychologists, neuroscientists and medical scientists have also proposed a variety of yawning principles, more than 20 in total. But so far, there is still no generally accepted conclusion in the academic community about the cause of yawning.

Physiological effects of yawning

Putting aside the fact that there is no clear conclusion on the reason so far, scientists have actually done a lot of research on the physiological effects of yawning.

For example, the wide-open mouth inhalation action of yawning has a pulling effect on various organs in the mouth and nose area. When we are on a plane and the plane is climbing or landing, our ears often feel a little uncomfortable due to the change in air pressure in the cabin. Yawning at this time can relieve this discomfort. This is because inside our ear canal, there is a diaphragm structure called the eardrum, which separates the internal structure of the ear from the external auditory canal. When the external air pressure changes, the pressure on both sides of the eardrum changes and is pulled, which will make you feel uncomfortable. However, there is a Eustachian tube in the middle ear behind the eardrum that leads to the pharynx. Normally, this thin tube, which is about three centimeters long, is closed, but when we do exercises to move the pharynx, such as yawning and swallowing, it may be temporarily opened. In this way, the middle ear will be connected to the open mouth through the Eustachian tube, so that the air pressure on both sides of the eardrum can be balanced and no longer feel uncomfortable.

On the other hand, the nasolacrimal ducts that connect to the nasal cavity from the corners of the eyes will be temporarily closed by the yawning action. As a result, the excess tears that could have flowed into the nasal cavity in time through them will have nowhere to go when yawning. Coupled with the deformation and compression of facial muscles when yawning, the phenomenon of "tears when yawning" may sometimes occur.

Yawning is contagious, not just in humans

However, the most interesting effect of yawning is that it is "contagious" between groups. This phenomenon exists not only in humans, but also in social animals. Zoologists have found that from primates such as gorillas, gray wolves of the canidae family, to the parrot family of birds, "yawning" has become an "international culture" of social animals.

Psychologists believe that this contagious yawning comes from the empathy between social animals for each other's states, that is, the perception of the physical and mental states of their companions. By imitating the behavior of their companions, group members who "yawn continuously" can quickly wake up in sync and regain alertness to stress or even crises in the environment. On the contrary, even if it is the same species, if there is a lack of empathy, yawn contagion may not occur.

Yawning has multiple meanings, not just about being sleepy

Yawning may seem like a normal daily behavior, but it actually reflects a variety of complex emotions and meanings.

For example, an important piece of evidence that psychologists use to explain yawn contagion is that patients with mental illness who have difficulty “thinking in sync” with most people rarely yawn infectively with others. Even when alone, patients with mental illness yawn less often than most people. A small yawn actually reflects our mental health status.

In addition, after we grow up, the emotions expressed by yawning are also very complex. Although yawning is almost always associated with sleepiness and boredom at the cultural level, many people yawn when they are nervous. For example, many paratroopers preparing to jump into the battlefield yawn involuntarily while lining up to jump out of the cabin. Some athletes also unconsciously open their mouths before preparing to go all out on the field.

Among animals, yawning with the mouth wide open and teeth fully exposed can even be used as a warning signal. Among primates, when two male monkeys are ready to compete for the throne of the monkey king, they often have a "yawning" confrontation first, using a full and violent display of the power of huge canine teeth to scare off the opponent as much as possible, and strive to "win the enemy without fighting." For more ferocious carnivores, when they accidentally meet in a narrow road in the mountains and wilderness, yawning will also occur frequently. At this time, yawning has completely lost the symbol of sleepiness, but has become a deterrent action to show fangs, move the muscles of the jaw, and take deep breaths to "boost and accumulate power" in preparation for war.

It can be said that yawning, as a neural reflex action, has actually been formed and fixed in evolution. Although it is a seemingly simple little action, it has very complex meanings and scientific principles that are still difficult to understand.