Basically it's called the POWER-TO-BE-CONSCIOUS and all sentient beings have this as they are IN IT, etc. It is the POWER of that which is.. some call it GOD. Others will call it a comglomeration of brain and other cells, etc. as a total dynamic unit, etc.
But how can it be proved? I can observe that you are conscious because we are communicating and you can observe the same in me becasue I am communicating with you. But if i'm asleep or unconscious then I can't prove it to you. The only way you can prove it is by saying I am conscious.
If a person can not speak or write or do sign laguage then how do you know they are concious?
I'm defining consciousness as thought in that I think to myself and reason with myself (I know I'm conscious) or I'm communicating to another (they know I'm conscious).
Like I said before how can it be proven or demonstrated. The answer is it can only be done by me communicating either me telling you via talking or writing it down or sign language.