yawning... is a way for the body to cool the brain...volunteers yawned more often in situations in which their brains were likely to be warmer...To prove their theory that yawning regulates brain temperature when other systems in the body are not doing enough, the researchers took advantage of the well-established tendency of people to yawn when those around them do — the so-called contagious yawn...The volunteers were asked to step into a room by themselves and watch a video showing people behaving neutrally, laughing or yawning. Observers watching through a one-way mirror counted how many times the volunteers yawned...Some volunteers were asked to breathe only through their noses as they watched. Later, volunteers were asked to press warm or cold packs on their foreheads...“The two conditions thought to promote brain cooling (nasal breathing and forehead cooling) practically eliminated contagious yawning,” the researchers wrote.
The study may also help explain why yawning spreads from person to person...A cooler brain, Dr. Gallup said, is a clearer brain...So yawning actually appears to be a way to stay more alert. And contagious yawning, he said, may have evolved to help groups remain vigilant against danger.
Thursday, July 05, 2007
Yawn to cool your brain?
A curious and slightly flakey bit: Eric Nagourney in Tuesday's Science section of the NY Times describes work by Gallup et al (PDF here) published in the Journal Evolutionary Psychology. It seems to me they might have actually measured brain temperature instead of just speculating about it. Nagourney notes the proposal by Gallup et al. that: