Before u read this, get a pen & paper. Use it to keep track the number of times u yawn while u are reading this page. You may find that just thinking and reading about yawning makes u yawn. The results may surprise u. Did u yawn yet? If u did, make sure u count it.
Everyone yawns. However, the reason why we yawn is a bit of a mystery. When we're bored, we yawn. We assume that we yawn because our bodies are trying to get rid of extra CO2 and to take in more O2 but the researchers found thateven when we exercise (breathe faster), the number of yawns during, before and after exercise was not different. Therefore, it appears that yawning is not due to CO2/O2 levels in the blood but are controlled by different mechanisms.
Why do we yawn? A researcher suggests that yawning is like stretching. It increases blood pressure and heart rate and also flex muscles and joints. If u try to stifle or prevent a yawn by clenching your jaws shut, the yawn is somewhat "unsatisfying". In 2007, researchers proposed that yawning is used to cool the brain. So, how many times did you yawn?
When talking about yawn, I am very sensitive... Till this word, I had been yawning for about more than ten times... and... still... arg!!! I've got enough jaws streching now. What about you?
"A yawn is quite catching you see. Like a cough. It just takes one yawn to start other yawns off."
- Dr. Seuss (in Dr. Seuss's Sleep Book, New York: Random House, 1962)