I wear my hoodie (hood on a Jacket) every day. Apparently, when a person's brain temperature becomes too elevated, it triggers a yawn to cool down the brain. So I ask, do you think wearing a hoodie a lot elevates the brain temperature?

http://www.aoma.us/PDFs%20and%20Documents/2011%20GA%20American%20Open%20Martial%20Arts%20Win ter%20Championship.pdf

Yawn coming on? Go ahead, rev up your brain - Chicago Tribune (http://articles.chicagotribune.com/2010-07-03/health/sc-health-0630-yawn-20100630_1_thermoregulatory-dysfunction-yawning-gordon-gallup)

What little I have read on it, it appears it is talking about "cooling" your brain is from use, not outside temp. More of an internal temp the comparison of a computer, when in higher use it gets hotter.