Why do we yawn?

by | Jul 19, 2017


The average yawn is six seconds long and we average eight yawns a day. Humans begin to yawn while still in the womb.  Yawning is not limited to humans – snakes, fish, cats and dogs, among others, all yawn.

What causes yawns?  Scientists are not completely sure what causes yawns. The leading theory is that yawning helps regulate the temperature of the brain. Yawning causes a slight decrease in brain temperature  because the act of yawning cools blood in our heads and causes cooled blood to enter the brain. In studies of mice an increase in brain temperature was found to precede yawning. Once they yawned, the brain temperature of the mice decreased. Thus, yawning is likely a thermoregulatory mechanism for the brain – but this is not 100% settled as the reason.

Have you ever noticed that yawns are contagious?  Intentionally, take a big yawn and see if those around you yawn soon after. Yawns become contagious to people between the first and second years of life. Why is yawning contagious?

Again, there is not certainty why yawning is contagious. Likely contagious yawning results from a combination of subconscious mimicry as well as empathy. Studies have found that yawning is contagious in about 70% of people and that merely seeing a picture of a person yawning or reading about yawning can spur a person to yawn. The contagious nature of yawning is not limited to humans.  Both chimpanzees and dogs have been found to yawn in response to a human yawn.

Question – did you yawn while reading this IFOD?

1 Comment

  1. The picture of that baby yawning totally made me yawn!

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