Why do we yawn ?
We yawn whenever we feel sleepy , tired ,or bored . At such times , our body relaxes and our breathing becomes shallow. When this happens , we open our mouth wider, and yawn to take in extra air. This helps to bring more oxygen into blood . The extra oxygen speeds up the circulation , and stretches the muscles . Yawning also moves more carbon dioxide out of the blood .
Another theory is that yawning stretches the lungs . Stretches and yawning may be a way to flex muscles and joints , increase heart rate ,and feels more awake .
On a lighter note , yawning seems to be contagious. If you yawn in class , you'll probably notice a few other people will start yawning , too. Even thinking about yawning can get you yawning.
We yawn whenever we feel sleepy , tired ,or bored . At such times , our body relaxes and our breathing becomes shallow. When this happens , we open our mouth wider, and yawn to take in extra air. This helps to bring more oxygen into blood . The extra oxygen speeds up the circulation , and stretches the muscles . Yawning also moves more carbon dioxide out of the blood .
On a lighter note , yawning seems to be contagious. If you yawn in class , you'll probably notice a few other people will start yawning , too. Even thinking about yawning can get you yawning.
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