ah, light 'jazz' is good for you

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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).

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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Printed on Thu Oct 04 03:00:57 BST 2007

[MoGrubb]

Huh, I did not realize that.

[BruceH]

That's funny, for me it's just the opposite---yawning always makes me feel like going to sleep.

[jazzbo]

Hey Bruce, you and me both. It's the opposite of a transition to alertness!