Answers

2015-09-08T14:58:43+05:30
We yawn when we feel sleepy because when we feel sleepy the oxygen in our body reduces and when we yawn we take extra oxygen for our body as our brain need oxygen to function properly
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2015-09-08T15:00:51+05:30
When we feel sleepy, it means we are tired and oxygen reduces in our blood. we yawn to intake more oxygen which our brain need to function properly and help us keep alert.
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