Yawning helps keep you alert?

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In life, we often find such an interesting thing: when a person starts to yawn, the people around them will also unconsciously follow, as if yawning will be "contagious". Yawning is so commonplace that humans do it all the time. However, the science behind this everyday behavior remains less clear.

Recently, biologists from the State University of New York found that the phenomenon of yawning contagion not only occurs in humans, but also occurs in other social animals, such as chimpanzees and lions. Also, probably all vertebrates yawn to regulate their body state.

In general, yawning is associated with fatigue, boredom, and sleepiness. When people are tired, carbon dioxide in the blood increases, which stimulates the breathing center of the brain, causing deep breathing activities, that is, yawning. By supplementing a large amount of oxygen and exhaling carbon dioxide at one time, it can restore the blood oxygen concentration and maintain the normal work of the brain.

However, the study found that yawning begins with an increase in the excitability of the cerebral cortex. When the human brain is overheated, the expansion and contraction of the maxillary sinus allows cool air to enter the brain, which can cool the brain and keep awake. Therefore, changing the temperature of the environment as well as the temperature of the individual brain can effectively control the frequency of yawning.

As for why yawning is contagious, research suggests that it is a complex social behavior. Yawning tends to occur at certain times of the day when you are overactive or depleted of activity. If yawning is a sign of a person's diminished alertness, then seeing a person yawning may in turn increase the observer's alertness. Therefore, the spread of contagious yawns in the entire group may increase the vigilance of the entire group.

In the experiment, the researchers showed the participants a series of images, including a threatening snake and a non-threatening frog, and calculated how quickly they could distinguish the images after seeing other people yawning. . The results showed that their ability to identify and spot snakes, a response to threatening stimuli, improved rapidly, while their ability to spot frogs was unaffected.

In addition, yawn contagion also has individual differences, and it is more likely to appear in the "empathetic population" . Studies have shown that children with autism are more indifferent to yawning than normal children of the same age. This partly supports the link between yawn contagion and empathy. Therefore, people with insufficient communication and social skills are likely to be less contagious from yawning.