For the full text see here. The fourth line from the bottom of the linked text is:
When he'd finished attaching the earring he unconsciously put his mouth to the door's ear.
I don't understand 無意識のうちに. I assume it means "unconsciously". But isn't 無意識 a na-adjective that means unconscious? Why can't I just use 無意識に?
I would have read 無意識のうちに literally as "while unconscious", but I'm quite certain that is the wrong interpretation.
What is going on here?
Edit: Thanks for the comments so far, but they are missing the point. I believe that subconsciously, unconsciously and unawaredly (if that's a word) all have similar meaning. I'm not confused about the person being able to do something while his brain is shut down. The main focus of my question is on why のうちに is used instead of just に and whether this is a grammar point that applies more generally.