Why are yawns contagious?!
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Answers:
Yawning is the result of the relaxation of muscles associated with inspiration and expiration so much so that enough oxygen is not getting to the lungs and the mouth is forced open. It occurs during bordem or fatigue and in some instances anxiety.
Yawns aren't directly contagious, it just seems that way. Most of the time if you see a yawn it is because the other person is relaxed and you're relaxed too.
Other Answers:
My Professor told us in my Human Physiology Class.
They are contagious because at sea level the pressure of Mercury is 260 (260mm Hg). Now when you breather in you have a +4 and when you breathe out you have a -4, therefore you are at 260 mm Hg at all times.
Now when someone yawns, they are taking in more than a +4, which then leads to someone else yawning because they have less than 256mm Hg around them. So to make up to get back up to 260 mm Hg that person takes in more.
In short, you have a (+) or (-) 4 pressure, and if it goes less than a -4 you yawn, which leads to someone else yawning.
Source(s):
My Professor
I watched a program this past weekend about this. They did a study on it and realized that it was just people mimicking people when they yawn even though they don't even realize they are doing this. I admit it is really contagious though when a person yawns, even on tv, it makes me yawn alot!
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