Yawning is caused by a state of tiredness, overworking, hunger and boredom. It is also caused by lack of stimulation and can be quite infectious. Yawning in itself is a reflex action that involves inhaling of air which stretches the eye drum and is followed by exhaling of air. Visit http://en.wikipedia.org/wiki/Yawn, for more information.
2 years ago
Last edited at 7:34AM on 12/2/2011
I never researched this but my husband is somewhat intelligent and I asked him that once. He says if you notice, you dont yawn when you are lying down, like in bed or on the couch because your body knows you are relaxing. But if you are driving, sitting at your desk etc and are tired and unable to just relax, a yawn becomes a natural reflex forced on by your body. As you begin to yawn, you take a deep breath in which is providing your body with more oxygen which increases your heart rate and increases brain activity, hence making you slightly more alert and focused. My husband is a truck driver and says that truck drivers will sometimes force themselves to yawn to stay awake and alert while driving. Now, this could all be nonsense, but scientifically, it makes sense. Hope this helps