Why Do We Yawn?

Why Do We Yawn?Have you ever wondered why you yawn? Have you ever started yawning the minute you see someone else doing it? Yawning is a common bodily function that we don’t pay too much attention to until we yawn at the wrong time or in the wrong place. To some extent yawning remains a mystery, but here is what scientists do know about it.

Yawning can be contagious. The mere suggestion of it – like reading this – may cause you to yawn, or you may do so when you observe another person yawning. (This well rested writer started yawning while writing this.) We’re not the only ones who do that. Chimpanzees and members of the wolf/dog family experience contagious yawning, too. Scientists think that yawning spreads because we feel empathy towards those we know – and those who are yawning.

A study posted in the research journal PLOS One seems to support that theory. Researchers showed one group of chimpanzees a video of a second group of chimpanzees yawning. The results of the study showed that chimps were more likely to yawn when they were familiar with the chimps they observed yawning, indicating that empathy may play a role.

However, another study published in PLOS One contradicted that finding. In fact, researchers discovered no connection between contagious yawning and empathy or time of day. They did, however, find that older people were less like to “catch a yawn” from others.
Suffice it to say that more research is needed to understand why yawns spread between humans, chimps, wolves and dogs.

What causes yawning?
The causes of yawning remain theories as well, but scientists do have some thoughts on the matter.
A change of physical or mental activity: It’s commonly held that if you yawn you must be tired or bored. You might be surprised to learn that a yawn causes the heart rate to rise quickly. Scientists believe that yawns may actually help us to change our physical or mental state from one of alertness or high activity to a quieter, less active one. For example:

  • A yawn could indicate that the body is tired and ready to sleep.
  • It could mean that the brain is becoming bored and is moving from a state of attentiveness to one of daydreaming or distraction.
  • After playing sports or exercising a yawn could indicate that the brain is transitioning to a lower state of activity.

More oxygen for the body:
Yawning may simply be a different type of breathing for the body. A yawn takes in lots of air and causes the heart to beat faster. As a result, the body takes in more oxygen. Researchers think that yawns may occur when the body knows it needs fresh oxygen in the blood.

Air conditioning for the brain
Believe it or not the best temperature to cool an overheated brain and the body’s circulatory system is about 68 degrees Fahrenheit. Researchers theorize that yawns tend to occur more often at that temperature so the body can take in perfectly heated and cooled air. The heart beats faster during a yawn and that causes blood and spinal fluid to circulate through the body, cooling down the brain.

An evolutionary cell phone:
Some scientists believe that our earliest ancestors may have used yawns to communicate to fellow human beings before speech was developed. They could have informed others that the yawner was bored, sleepy, becoming less active or more aggressive by showing teeth.

As you can see, there are no hard facts about the causes of yawning or why they are contagious. As a result, there really is no way to know how to prevent them. Suffice it to say that a good night’s sleep and stimulating activities may prevent yawns, and you can always look away when you see someone else beginning to yawn so you won’t catch it!

 

References
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0018283
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0091773

 


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