http://www.newscientist.com/article/mg19426104.400-yawning-may-boost-brains-alertness.html
Yawning may boost brain's alertness
* 02 July 2007
* NewScientist.com news service
* Rowan Hooper
Yawning is not something we usually aim to provoke among our readers,
but have a yawn now. Does your brain feel cooler? Do you feel more
attentive? According to psychologists Andrew Gallup and Gordon Gallup
of the State University of New York at Albany, that is why we yawn:
to boost blood flow and chill the brain.
Not only that, brain-cooling explains why you can "catch" a yawn,
says Gordon Gallup. "We think contagious yawning is triggered by
empathic mechanisms which function to maintain group vigilance." In
other words, yawn-catching evolved to help raise the attentiveness of
the whole group.
The pair recruited 44 college students to watch, individually, films
of people yawning and recorded the number of contagious yawns each
volunteer made. Students were told to inhale and exhale in one of
four ways: strictly orally; strictly nasally; orally while wearing a
nose plug; or just breathe normally.
Fifty per cent of people told to breathe normally or through their
mouths yawned while watching other people yawn, while none of those
told to breathe through their noses yawned. The researchers also
found that subjects who held a cold pack to their forehead did not
catch yawns from the film, while those who held a warm or
room-temperature pack yawned normally (Evolutionary Psychology, vol 5, p 92).
"Subjects who held a cold pack to their forehead did not catch yawns,
while those who held a warm pack yawned normally"
Blood vessels in the nasal cavity send cool blood to the brain, so
breathing through the nose or cooling the forehead cools the brain
and eliminates the need to yawn, says Gordon Gallup. He argues that
brains operate more efficiently when cool, and that yawning enhances
brain function. "According to our hypothesis, rather than promoting
sleep, yawning should antagonise sleep," he says.
"Paratroopers report yawning before they jump," says Robert Provine
of the University of Maryland, Baltimore County. "Yawning signals a
transition between the behavioural states of wakefulness and
sleepiness, and boredom to alertness."
From issue 2610 of New Scientist magazine, 02 July 2007, page 14
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((Udhay Shankar N)) ((udhay @ pobox.com)) ((www.digeratus.com))
