What is the reason beyond yawning?
a) lack of oxygen
my teacher told me that it is because of lack of oxygen .
but i think it can be because of sleepiness,
we need oxygen to break food and release energy and food digests faster or food is broken down with the help of oxygen faster when we are asleep, so we feel like sleeping after having food.so in many cases it can be said that yawning is a symbol of sleep .