College College Biology and Chemistry College Mind, Brain, and Behavior TSS

Why Do We Yawn?

Understand the different theories of yawning and why yawning is contagious.

Image from

“Snorlax, use Yawn!”

Snorlax yawns. Charizard falls asleep.

Okay, well, GameFreak had to balance the Pokemon move “Yawn” so that it wasn’t a useless move like “Splash”. However, in real life, if Snorlax yawned in front of Charizard, chances are Charizard would yawn too.

Yawning is an interesting topic in the science field. We have yet to confirm the exact reasons why we yawn, but there are some theories which explain why people yawn. And yes, one of those theories explains why yawning can be contagious.

During his postdoctoral research at Princeton University, Dr. Andrew C. Gallup, Ph.D., theorized that yawning is a physiological response for the body to cool down the brain (1). He experimented with multiple subjects ranging from humans to rats and discovered that each subject’s blood flow increased from the forceful opening of the mouth while yawning. Simultaneously, the body takes in a large amount of breath which compels the brain to release hot spinal fluids and blood, ultimately cooling the brain.

Gallup conducted his experiment in Tucson, Arizona to test his hypothesis that yawning occurs more in cooler environments than warmer ones (1). He went there twice – once in the winter time (71.6° F) and again during the summer (98.6° F). In a group of 80 people, 45% of them yawned during the cool weather compared to the 24% who yawned in the warm temperature, confirming Gallup’s hypothesis (1). Yawning also occurred at around 20° C, or 68° F, which is the ideal temperature for temperature control of the brain and blood (2). Studies altogether showed that the brain, regardless of the temperature, eventually cooled down after yawning.

There is another popular theory on why we yawn. Dr. Adrian G. Guggisberg, MD, a physician at the University of Geneva, argues that yawning is a social mechanism instead. Guggisberg argued that if yawning was indeed to cool the brain during warm settings, there should’ve been more people in Gallup’s experiment to yawn during the summer. Guggisberg claims that Gallup’s theory fails to regulate body temperature when we actually need it (i.e sweating) (1).

Guggisberg insists that yawning is an indicator of one’s level of empathy. This theory explains why yawning can be contagious; a person yawning informs someone else that he/she is either sleepy or bored. Yawning, as Guggisberg would suggest, is an expression to communicate one’s unpleasant experience for his/her current situation. Gallup attacks Guggisberg’s theory arguing that it is too vague to be considered an actual communicated expression (1).

There are other theories suggesting why we yawn. One of them is the brain’s method to change our alertness; before bed, the brain tells the body to get ready for bed; during boredom, the brain tries to “reawaken” the person to stay on alert; after an exercise, the brain transitions our awareness from high to low due to energy changes (3). There are further studies from Baylor University that confirmed yawning to be an act of empathetic bonding (2)

However, yawning excessively can be dangerous. Excessive yawning could be a symptom of various disorders: heart conditions, brain conditions, or sleep disorders (3). Maybe that’s why Snorlax can only use “Yawn” 10 times. Could also be why “Yawn” bypasses accuracy checks and always hits the opposing Pokemon (sorry, Pokemon nerd activated).

Whichever theory you believe, know this: you can always pull the Gallup Theory card when your professor, your parents, or whoever becomes insulted when you yawn in front of them. Simply declare that you cannot control physiological mechanisms that the body forces to cool down your brain.

By the way, even looking at the word “yawn” can make you yawn. Yawn, Yawn, Yawn, Yawn, Yawn, Yawn, yaaaaawwwwwnnnnnn, yaaaaaaaaawwwwwwwwnnnnnnnnnn

yawn. Did I get you?





Kenny Jung is a first year at UC Merced where he majors in computer science and engineering. He has many recognitions such as QuestBridge College Prep Scholar 2017 and National College Match Finalist 2017, SCS Noonan Scholar, Fiat Lux Scholar, APIASF Scholar, and Caruso Scholar. In addition to writing for The Student Scientist, he takes part in a non-profit organization called Project Magnify which he helped become established in 2017.

0 comments on “Why Do We Yawn?

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

<span>%d</span> bloggers like this: