Some years ago I met a man who had recently come out of a coma after 2 years. He told me that during that time he had been aware of everything around him , he had heard everything and felt everything , but could not respond.
He said he suddenly came to and the first thing he said was "STOP THOSE B****DY NEEDLES ! " . Apparently every day nurses and doctors would stick needles in him to test for any response.