How often do you yawn each day? Only once? Or ten times? How long is each yawn? Five seconds? Or ten? Do you affect others with your yawn? And do others also mean animals? Yawn may be just an ordinary reflex action, but there is much to learn about it.
Yawn is the opening of the mouth, whether voluntarily or involuntarily, with a long, full inspiration of the breath. It is a reflex of simultaneous inhalation of air and stretching of the eardrums. The act is called as pandiculation.
There are several theories why humans yawn.
These are the following:
a. Yawning occurs when the blood contains too much carbon dioxide that it needs the influx of oxygen which a yawn can provide. However, studies have shown that yawning actually reduces oxygen intake compared to normal breathing.
b. Yawning is a natural reflex to stretch the muscles. It also helps keep the body ready for action, just like stretching before any exercise.
c. Another theory is that yawning is a way of controlling brain temperature. Similar notion states that it is in fact used for regulation of body temperature. This can be attributed to the influx or outflux of oxygen in the brain or body.
d. Yawns are also caused by the same chemicals, called as neurotransmitters, inside the brain that affect emotions, mood, appetite, and other phenomenon. This is why yawning is commonly associated with tiredness, stress, overwork, lack of simulation, and boredom.
Yawning has been observed to be contagious. Looking at another person’s yawning face, even reading, thinking, or seeing a yawning picture can cause a person to yawn. This indicates empathy, or that yawning is just an appreciation of other people’s behavioral and physiological state. They yawn, so we yawn as well. The contagious yawning is supposedly caused by mirror neurons in the brain that urges human to imitate certain actions. Contagious yawning has not been observed in humans alone but also with other animals like dogs.
In animals, yawning can mean the following:
a. As a warning signal. Baboons yawn and display their large canine teeth to threaten enemies. Guinea pigs yawn to show anger or dominance.
b. As part of courtship ritual, like in penguins.
c. As exercise, like in snakes to realign their jaws after a meal.
d. As means to regulate oxygen and body heat, like in fishes.