Why Are Yawns Contagious? Theories Abound

You've probably experienced it: you see someone yawn, and before you know it, you're yawning yourself. And it's not just in person. Yawns can be contagious through videos, pictures, and even audio and text.

Has reading this made you yawn yet? If so, you're not alone. But why do we yawn, and why do we yawn when we see others yawn? Is yawning really contagious?

Why Do We Yawn?

There is no scientific consensus on why we yawn.

One theory suggests that when we're feeling tired, we stop taking deep breaths, leading to a build-up of carbon dioxide in the body. Yawning might be a specialized form of breathing that quickly brings in oxygen and expels carbon dioxide, even more efficiently than deep breathing.

Other theories propose that yawning is meant to cool the brain, or to stretch internal organs like the lungs and tissues, helping to wake the body up. Additionally, boredom with the current situation can lead to yawning, such as during a lengthy and complex meeting. If you are not engaged, you may involuntarily yawn, using body language to express your disinterest.

Do All Animals Yawn?

Most animals yawned, as you can observe in cats and dogs. Yawning is a primitive reflex in many animals that originates in the brain stem. Since the human brain stem is similar to that of other mammals (as well as birds and reptiles), it makes sense that most animals yawn. In fact, birds, reptiles, mammals, and even some species of sharks may yawn—and animals with larger brains tend to yawn for longer periods.

Why Are Yawns Contagious?

It is estimated that about 40% to 60% of adults worldwide will yawn in response when they see someone else yawning.

The contagious nature of yawning is widely believed to be associated with the human mirror neuron system. Mirror neurons are a special group of neurons in the brain that are activated when we observe the behavior of others and also play a role when we perform the same or similar actions ourselves. These neurons appear to play a key role in imitation and learning processes, helping us to understand and simulate the behaviors of others.

In the case of contagious yawning, when we observe someone else yawning, our mirror neurons may be triggered, leading us to unconsciously imitate this behavior. This phenomenon has sparked great interest in the fields of psychology and neuroscience because it reveals how humans establish social connections and empathy through imitation with others.

There are several other theoretical explanations for why yawning is contagious:

The Chameleon Effect

If yawning is considered "contagious," it might be more accurate to call it "mimetic." Yawning mimicry is more like the chameleon effect, which refers to subtle, unconscious mimicry behavior.

Transference in Psychoanalysis

Yawning contagion is also related to personality. One study conducted personality tests on college students and then showed them facial videos, including people yawning. The results showed that students with lower empathy scores were less likely to yawn.

The Manam Effect

The Manam effect refers to a herd mentality. When people receive information from others around them, they can unconsciously create a suggestion, and they will automatically use the behavior of others as a reference for their own behavior.

What Are the Benefits of Yawning?

Yawning may seem like a signal of tiredness, but it harbors many lesser-known benefits.

Relaxing the Whole Body

Research indicates that a yawn lasts for about 6 seconds during which a person closes their eyes and becomes less aware of sounds, allowing for complete relaxation of the nerves and muscles throughout the body. The deep breathing action associated with a yawn prompts an increase in oxygen levels in the blood and the expulsion of more carbon dioxide, thereby invigorating one's energy levels.

Exercising Throat Muscles

Yawning engages the muscles in the throat, increasing their strength. During a yawn, the nerves and muscles throughout the body relax, entering a state of complete looseness, which can also alleviate symptoms of snoring caused by relaxed throat muscles.

Stretching Lung Tissue

Yawning allows the lungs to expand, reducing intracranial pressure, and increasing both the venous return to the heart and the cardiac output. This, in turn, increases the oxygen content in the blood and improves brain oxygen deprivation. It can be viewed as a form of the body's self-preservation mechanism.

Promote Blood Circulation

Research from the State University of New York at Oneonta suggests that frequent yawning can promote blood circulation, and the longer the yawn, the stronger the cognitive ability. The human brain cortex has about 10 billion neurons, with the average duration of a yawn being 6 seconds. In comparison, mice yawn for less than two seconds. Therefore, researchers believe that the number of neurons is the main factor affecting the duration of a yawn, and those who yawn longer tend to have better cognitive levels.

Regulate Brain Temperature

A study found that yawning is related to the temperature of the brain. Fatigue and lack of sleep can cause the deep brain temperature to rise, thus necessitating a yawn to cool down. Researchers discovered that the relationship between yawning and ambient temperature is the most significant. Yawning is most likely to occur around 20°C. If the external environment is too cold, the brain does not need to rely on yawning to cool down. If the temperature is too high (such as around 37°C), yawning has little effect on cooling, and the body naturally reduces yawning.