What Causes Those "Workout Yawns?"

Hey Sam, I noticed the other day when I was working out, that I yawned 4 or 5 times. I had gotten a good night’s sleep the night before. What’s up with that? --Bronson

Hey Bronson. I get this question a lot. When you yawn, you are also stretching your neck and head muscles in order for the veins to constrict and move blood (and oxygen) more rapidly to the brain. This action is triggered by carbon dioxide or hypoxia.

There's really no definitive scientific explanation for this phenomenon. However, I did some research and found a few possible causes (and some fun, "yawn facts.")

The first hypothesis is that when a room builds up carbon dioxide, the carbon dioxide causes you to become sleepy, so you begin to yawn (even if you're not feeling tired).

Other explanations:

A recent theory is that yawning is how your body regulates its own internal temperature.

Some claim that yawns are caused by the same chemicals (such as serotonin, dopamine, glutamic acid and nitric oxide) in the brain that affect emotions, mood, appetite and other phenomena. As more of these compounds are activated in your brain, the frequency of yawning increases.

Some folks are actually superstitious about yawning! A few Christian sects believe that yawning is brought on by the Devil who "sends evil demons to enter a person's body when your mouth is open." (This is why some people cover their mouths when they yawn).

Other superstitions:

* A yawn is a sign that danger is near.
* Counting a person's teeth robs them of one year of life for every tooth counted. This is why some people cover their mouths when they laugh, smile, or yawn.
* If two persons are seen to yawn one after the other, it is said that the one who yawned last bears no malice towards the one who yawned first.

I hope this helps! --Sam