A contagious phenomenon

Have  you all noticed that every morning we wake up by either stretching ourselves wide or having a huge splurge in and splurge out of air.We are sitting idle just gaping at the sky ,and are lonely ;or are too busy with loads of work and need to stay awake ,then too we have this wide yawn and stretch.Some of the common situations ,where you and me would have experienced a loud /silent yawn:  A  lecture  session is going on at college classroom  and we have our involuntary reflex yawn and consequently end up going out of the classroom .Ur friend/wife is talking some "so called interesting topic ,or narrating a story /gossip",and your yawn makes her frown:)So your yawning would signify the opponent person that you are "bored". Even a very persistent strenuous effort to avoid this would be in vain,because this phenomenon is so involuntary!My grandma always used to say that somebody is trying to remember me ,when I was yawning too many times ;so this was a very common myth i heard from lot of people later too.There may be a lot of other myths associated with it too.Also, if you noticed ,if we see someone yawning,we too catch up that yawn ,feels as is it was some "contagious disease" to catch up!If you are sitting with a group of friends and having a talk,aDoctor's waiting room or a reception area where lot of people are waiting you have a yawn ,and all other too!or imagine the scene of a meeting at a conference hall,where one ignorant person yawns and then the whole bunch of people repeats this as if it was a hierarchy to be passed on!Some people may even have a yawn with just the thought or discussion of yawn ,no wonder if some of my readers catch up a yawn!he he. And as a dentist ,i have one small piece of advise to all my readers :Donot yawn too wide ,because who knows?you may tend to fix your jaws or have a dislocation of your jaw joint next to the ears(we call it as Temperomandibular joint/TMJ) .I am serious!      
           ( The question:why do we yawn? I went through a few articles and found out that' yawning' had lot of theories to explain its evolution.The one which i felt most suitable was that we yawn to incorporate a lot of oxygen within our body.When we are sleepy ,and we need to stay awake ,we need to get rid of the excess CO2 and stuff in as as much of o2 into our body.So a yawn can help us achieve this;that's because when we yawn ,our lungs expand and pushes our diaphragm down ,and we breathe in lots of oxygen ,and breathe out the excess co2 in our body.so how's the logic?sounds gud right? But then this theory was not approved by all the scientists and researchers and they felt  lot of possible reasons.Wickipedia narrates the possibility of some neurotransmitters like dopamine,serotonin,nitric oxide being activated as the prime cause of yawning.Also wickepedia states that the "imitation of yawning ";that is when" one person yawns ,the other too does"can be related to showing some sort of "empathetic behaviour".I can explain this :We humans have a tendency to always relate ourselves to another individuals situations and experiences ;same happens when a person "yawns",we would be trying to relate  and experience that person's bore dome and thus involuntarily we would also yawn!strange but true.Also it is also implicated that some "mirror neurons " present at the frontal cortex in brain may also be responsible for this imitation act.)

Reference:   http://en.wikipedia.org/wiki/Yawn
                   http://health.howstuffworks.com/mental-health/human-nature/behavior/question572.htm