Question

How do we feel unconsiousness

Answer 1

Here is your answer.
we may become temporarilyunconscious, or faint, when sudden changes occur within the body. Common causes of temporaryunconsciousness include: ... syncope, or the loss of consciousness due to lack of blood flow to the brain.
There are 35 conditions associated with feeling faint and loss of consciousness. 

Hope it helps you.

Answer 2

we feel unconscious when sudden change occurs in body , like lack of blood in body ......