Why Do People Yawn?

Yawns are automatic reactions to an increased amount of carbon dioxide (CO2) in the blood. When people are exhausted, bored, fed up, tired, or being inactive, then their respiration slows down.

This phenomenon leads to a decrease in the level of oxygen, and an increase carbon dioxide level in the blood. Consider my very own example: When I was in college, I used to yawn a lot during my chemistry class in a huge lecture hall (I hate chemistry by the way).

By opening the mouth wide, and inhaling, yawns draw in a large amount of oxygen while ejecting the accumulated carbon dioxide from your blood, bringing your body back to its normal condition.

In other words, we can say it like this: Yawns occur when the body needs additional oxygen, and being exhausted is one of the factors that make this happen.

Unluckily, this biomedical explanation for yawning will cut little ice with your chemistry professor or manager, if he or she catches you yawning at a critical moment! You could practice controlling it for such critical moments.

All people yawn, from newborn babies to the oldest great-grandparent - and animals yawn too. But there are many opinions as to why people yawn.

Yawns oxygenate the blood, by widening and aerating the tiny lung sacs called alveoli, and by expelling carbon dioxide from the lungs.

If you see people yawning as they come out of the theater, do not assume that it was a terrible movie. Contrary to popular opinion, yawning isn't necessarily a sign of boredom. If you yawn, it simply indicates that you need more oxygen, and it is nothing but a reflex that forces oxygen into your lungs.

Another explanation is that yawning stretches the lungs and lung tissue. Stretching and yawning may be a way to flex muscles and joints, increase heart rate, and feel more awake.

The body's oxygen supply is depleted after a long period of shallow breathing, which commonly occurs when you are tired, under stress, or have been sitting still for a long period of time.

Yawning is not a sign of illness or abnormality, and rarely occurs during serious mental or physical disorders.

We yawn when our bodies are trying to get rid of extra carbon dioxide and to take in more oxygen.

When people are getting bored or tired, they breathe more slowly. As breathing slows down, less oxygen makes it to the lungs.

As a result, carbon dioxide builds up in the blood, and a message to the brain results in signals back to the lungs stating, "Take a deep breath," - and a yawn is the outcome.

Yawning is experienced basically when the body feels the lack of enough oxygen.

The reason behind yawning is a lack of oxygen to the brain.

Because you need more oxygen.

I accept that people yawn, when there is more Carbon Dioxide or when they need more Oxygen - but why do they yawn, when they see someone else yawning??