You’re Getting Very Sleepy: Why We Yawn

[Dantheman62]

For many people, the sight, the sound, or the suggestion of another person yawning is enough to set them on their own yawning fit. For me, even seeing my cat begin to yawn and stretch can induce a wave of fatigue that’s enough to make me feel tired.

We yawn when we hit the afternoon slump, and we yawn when we’re ready to call it a day, and sometimes we yawn for no good reason at all. Yawning is an involuntary act that’s shared by many species—not just cats and dogs, but monkeys, apes, other mammals, and even some reptiles. The truth is, not much research has been done about yawning and the reasons behind it, so it remains among the strange, unexplained body quirks that we puzzle over every day. A behavior exhibited by so many different species might appear to be vitally important, but in the case of yawning, its prevalence is anyone’s guess.

Open Wide!
A yawn is a peculiar set of gestures—the mouth gapes open, our abdominal muscles flex, the diaphragm pushes down, and we take in an extra-large breath of air. If you’re like me, watering eyes might also accompany your yawns. The whole process takes about six seconds. Yawns are highly recognizable and humans do them even before we’re born. Research shows that fetuses can yawn as young as eleven weeks old.

Many people yawn when they’re tired or drowsy. Indeed, yawns do accompany feelings of exhaustion or lethargy, but researchers haven’t exactly pinpointed why we yawn. Any ideas that seek to ascribe yawning to a particular purpose are simply theories, not proven medical explanations. The physiological theory of yawning is a popular assumption, and it hypothesizes that yawning results from a lack of oxygen and an overabundance of carbon dioxide.

The large draw of breath in a yawn theoretically enables us to take in extra oxygen and remove carbon dioxide from the bloodstream, but this theory has some big holes. If we yawn when we need oxygen, then why don’t we yawn while we’re exercising and our bodies are using up oxygen very rapidly? I’ve never been mid-workout, muscles screaming, and had to stop for a quick yawn.
Also, this theory has been tested and disproved; in a study, giving air with additional oxygen or carbon dioxide to the test subjects didn’t reduce or increase the frequency of their yawns.


http://www.divinecaroline.com/22178/...y-sleepy--yawn

[Swanny]

Time for bed