Why We Yawn...

[zengrifter]

Yawning - it will help keep you awake

By GWYNETH REES - 4th July 2007

It can catch you embarrassingly unawares - as Cherie Blair has discovered.



But rather than being a precursor to sleep, scientists say the yawn is actually
designed to keep you awake.

A study has found that when you yawn, the inhaled air reduces the temperature
of vessels in the nasal cavity, allowing cooled blood to be sent to the brain.

This chills the brain, making it more alert and able to perform better.

...more - http://www.dailymail.co.uk/pages/liv...n_page_id=1770