Why Are Yawns Contagious?

For many years, several theories have tried to explain why yawning occurs. However, for now there's no conclusive evidence. What do some hypotheses say? Find out here!
Why Are Yawns Contagious?

Last update: 10 June, 2021

Why are yawns contagious? Almost two-thirds of people are sensitive to the contagion of yawning. In other words, they’ll instinctively repeat this behavior if they see someone else doing it.

The fact is that, among the most common human behaviors, yawning is perhaps the least understood. Thus, scientists have yet to provide an explanation of why we yawn. Although, in any case, this behavior tends to be common in other animals such as cats, dogs, apes, etcetera.

Yawning usually occurs just before going to sleep, when we wake up, when we’re hungry or when we’re bored. Even just the fact that you’re reading this article can induce you to yawn. And have you noticed that they have an impressive contagious potential?

Theories on why yawning exists

If this behavior exists, it must be because it has some utility. Now, what could it be? For many years, several theories have tried to explain it. Let’s take a look at some of the most accepted ones.

Oxygenation theory

Its most distant antecedent seems to be in Hippocrates, who defended that yawning eliminated used air and renewed it with clean and fresh air. This hypothesis seems to correspond to the fact that, when oxygen levels decrease due to drowsiness, yawning would be a quick way of injecting oxygen into the organism.

In any case, this is a controversial theory which, as the researchers point out, hasn’t been tested yet. Therefore, the idea can neither be confirmed nor ruled out in its entirety.

a woman yawning at a computer
One of the theories about yawning suggests that it’s produced to give the body a quick injection of oxygen.

Activation theory

If we’re conscious, we yawn when our level of alertness decreases due to drowsiness, boredom, and so on. By yawning, we redirect our attention and it gives us a necessary extra boost of arousal. However, although it seems logical, the idea hasn’t been 100% empirically proven.

We shouldn’t rule out this theory, it’s just that we need more research to causally relate the level of arousal to yawning.

Body temperature theory

This is the theory that has gained the most traction in recent years, as it’s the one that provides the most convincing data. According to a study by Gallup, A. C., & Eldakar, O. T. (2013) yawning would help lower the temperature to cool the brain and get it to function better.

The data clearly indicate that, before yawning, there’s a temperature rise that drops rapidly after each yawn. If you want to eliminate yawning, putting a cloth with very cold water on your forehead has a similar effect.

Moreover, these data have been successfully replicated in other studies, so there’s considerable validity to the theory. However, the principal investigator of the study suggests that the above 3 theories are compatible with each other and that, although this theory has greater validity, we shouldn’t rule out the possibility of a relationship between the three.

A woman yawning.
That yawning helps regulate body temperature seems to be one of the most plausible hypotheses. However, other explanations haven’t been ruled out.

Why are yawns contagious?

As we explained, most people usually yawn when they see someone else do it and the same thing even happens to other animals. There are two theories that explain this; here are the details:

  • Yawning helps synchronize group behaviors. It’s part of imitation behaviors. For example, social animals tend to perform specific behaviors at the same time. For example, eating, moving, body posture, and so on.
  • The second theory refers to empathy. Thus, seeing someone yawning would activate the brain circuits of empathy, including mirror neurons, which act as an internal reflection of the movements we observe in others.

So, we’ve seen three theories that seem to simultaneously explain the reason for yawning. In addition, we went over some of the reasons why yawns are contagious. What’s your take on all this?

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  • Gallup, A. C., & Eldakar, O. T. (2013). The thermoregulatory theory of yawning: what we know from over 5 years of research. Frontiers in neuroscience6, 188.
  • Harvey, D. J., Merry, A. H., Royle, L., Campbell, M. P., & Rudd, P. M. (1996). Justice, nature & the geography of difference.
  • Isaacowitz, D. M., & Stanley, J. T. (2011). Bringing an ecological perspective to the study of aging and recognition of emotional facial expressions: Past, current, and future methods. Journal of nonverbal behavior35(4), 261.
  • Norscia, I., & Palagi, E. (2011). Yawn contagion and empathy in Homo sapiens. PloS one6(12).