🚀 go-pugleaf

In article <7841@tekecs.TEK.COM> mikes@tekecs.TEK.COM (Michael Sellers) writes:
>Here's *my* side issue:  I was recently asked why you yawn when you are
>tired.  I (somewhat smugly) replied that it was to get rid of excess
>CO2 in the bloodstream.  The question then became why does the amount of
>CO2 in your blood increase when you are tired?  I started to say something
>about accumulating waste products in your blood, but then remembered that
>the theory of sleep functioning as a way to get rid of accumulated poisons
>had been shot down a few years back.  So, what to say?  Why *does* CO2
>accumulate in the blood (plasma)?  You would think that its diffusion 
[reasons why it shouldn't accumulate. Maybe to expand the lower lobes of
 the lungs. Mike, I hope I did you justice.]

>			   Mike Sellers
>     UUCP: {...your spinal column here...}!tektronix!tekecs!mikes

My pet theory (unsubstantiated by any medical data) is that when you
are tired some part of your brain wants to go to sleep, but the
controlling, conscious part of your brain wants to stay awake. As a
result, under appropriate circumstances (little physical movement is
part of the requirements) your lungs or sympathetic nervous system go
into "sleep mode", allowing slightly higher CO2 concentration to build
up in the blood (this idea of less tight CO2 control when asleep is a
hypothesis of mine, not necessarily a fact). Then all of a sudden the
awake part of your brain realizes that there is too much CO2 and
yawns.  That's why yawns are contagious, because other brains also
notice "hey, I'm in high-CO2 sleep mode" and yawn.

Disclaimer:
The above is a product of my imagination and should not be construed as
having anything to do with reality. I am not a doctor or a biologist.

			Ed Biagioni
			decvax!mcnc!unc!john!biagioni
			seismo!mcnc!unc!john!biagioni
    			biagioni@cs.unc.edu