Yawning Helps You Stay Awake
Yawning may appear the height of
rudeness, but in fact your body is desperately trying to keep
you awake, according to research from the US.
Psychologists who studied 44 students concluded
that yawning sent cooler air to the brain, helping it to stay alert.
Yawning therefore delays sleep rather than promotes
it, the study in Evolutionary Psychology suggested.
The desire to yawn when others do so may also
be a mechanism to help a group stay alert in the face of danger.
The common wisdom is that people yawn because
they need oxygen, but the researchers at the University of Albany
in New York said their experiments showed that raising or lowering
oxygen and carbon dioxide levels in the blood did not produce
Their evidence suggested instead that drawing
in air helps cool the brain and helps it work more effectively.
In a study of the 44 students, researchers found
that those who breathed through the nose rather than the mouth
were less likely to yawn when watching a video of other people
This was because vessels in the nasal cavity
sent cool blood to the brain, they said.
The same effect was found among those who held
a cool pack to their forehead, while those who held a warm or
room-temperature pack yawned when watching the video.
"Since yawning occurs when brain temperature
rises, sending cool blood to the brain serves to maintain optimal
levels of mental efficiency," the authors wrote.
"So the next time you are telling a story and
a listener yawns there is no need to be offended - yawning, a
physiological mechanism designed to maintain attention, turns
out to be a compliment."