Why We Yawn
By Joan Whetzel
The two questions everyone asks, but no one has an absolute answer for, are (1) Why do we yawn? and (2) Why are yawns so contagious? All we have to do is see someone else yawn and we feel the urge to do the same. I found myself heading into fits of yawning just researching this article. I read the word yawn enough times, and I’m fighting them off like bees on at a honeycomb.
What Is Yawning?
Yawning is considered reflexive, an act that involves simultaneously inhaling deeply and stretching the eardrums by opening jaw widely. This is followed by exhaling the breath. Yawning is usually involuntary.
Causes of Yawning
The most common causes of yawning are fatigue and drowsiness. But there are other likely causes or triggers as well, such as:
· Illnesses that produce daytime sleepiness
· Vasogal reactions associated with heart diseases.
· Lack of sleep.
· Epilepsy.
· Brain tumors.
· Sleep apnea.
· Overwork.
· Boredom.
· Seeing others yawn.
· Talking to someone on the phone who yawns during the conversation.
Some theories which have not been substantiated include increased carbon dioxide levels in the bloodstream, a need for more oxygen (which is produced by the yawning), the urge to stretch, anxiety and stress, and to be caused by an increase in the same brain chemicals (serotonin, dopamine, nitric acid) that affect emotions, appetite, and mood while a decrease in yawns may occur as endorphins rise. Yawning is thought to increase the state of alertness, to control the brain’s temperature, and to reduce brain pressure.
Why Are Yawns Contagious?
One study in Finland confirmed that the contagiousness of yawning is pretty much unconscious (no surprise there) and that it bypasses the brain’s usual circuitry used when we consciously analyze and mimic the actions of other people. Many studies have been performed to try and determine the exact mechanism that produces the contagion, put the results of the testing have produced a lot of unrelated clues that are virtually indecipherable. The only things the studies agree on is that they can’t agree on, or determine, the exact reason that yawns are so contagious.
Resources
Wikipedia. Yawn.
http://en.wikipedia.org/wiki/Yawn
Medline Plus. Excessive Yawning.
http://www.nlm.nih.gov/medlineplus/ency/article/003096.htm
Right Diagnosis. Yawning.
http://www.rightdiagnosis.com/sym/yawning.htm
World Science. Why Is Yawning Contagious?
