Causes of yawning:-
Even though causes of yawning are not exactly known, it’s believed following are main causes.
* a state of cooling mind.
* as a state of psychological decompression after high alertness.
* increased carbon dioxide in blood and decreased oxygen level.
* a mental state of poor emotions or apathy.
* excess mental strain
* to maintain middle ear pressure yawning is a body mechanism.
* higher alcoholic content in food or alcohol intake.
* lack of sleep, lack of rest to mind.
* biochemical substance variation such as serotonin, dopamine, etc in the brain.