Are we boring you?
Research into yawning is not very exciting. Scientific studies tend to confirm what most people have known for centuries: that yawning is more common during the hour before bedtime and the hour after waking, that we yawn more when our level of interest drops and that yawning is "contagious.'
However, one commonly held belief about yawning--that it can occur as a response to a lack of oxygen or a buildup of carbon dioxide in the body-- may not be true. Robert R. Provine and his colleagues at the University of Maryland in Catonsville undertook to test that oft-cited but untested assumption, and found that yawning is neither a response to nor a means of regulating oxygen or carbon dioxide levels.
The researchers gave people different mixtures of oxygen and carbon dioxide to breathe, and found no correlations with yawning behavior. Indeed, their research suggests that yawning and breathing are triggered by entirely different internal states and are probably controlled by separate mechanisms.
As further evidence that yawning does not serve a primary respiratory function, the researchers note that yawning and breathing have different requirements with regard to their routes of inhalation and exhalation. While breathing can be performed satisfactorily through either the nose or mouth, the researchers report that subjects find it "very difficult, if not impossible, to perform a satisfying yawn with their mouth taped shut.' Moreover, they say, oral inhalation by itself will not produce a satisfactory yawn unless the jaw is free to move. "Subjects attempting to yawn with clenched teeth often reported the unpleasant sensation of being stuck in mid-yawn.'
So much for what the yawn is not. As for what it is, the researchers must concede that the yawn's true function "remains mysterious.'
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|Title Annotation:||research on yawning|
|Date:||Dec 5, 1987|
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