While i was studying in my bedroom, after our daily english class, i couldn´t avoid yawing 10 or 12 times, which made me remember one of the many topics we had discussed.
I read some theories about why do we yawn(what made me yawn even more :P). The first theory i found says something similar to what francis was trying to explain to us in class, that people yawn because they are bored or tired, so we don´t breathe as deeply as we usually do and our body take in less oxygen because their breathing has slowed. As a result, yawning helps us bring more oxygen into the blood and move more carbon dioxide out of the blood. However, this teory was discarded after several tests (studies have shown that breathing more oxygen does not decrease yawning).
Another theory 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.
I hope this information was useful. If someone finds another theory, i will be very interesting in reading it.
