noun; verb form: nonscious
a mental state that is similar in many ways to that of human consciousness, but is distinct in some salient sense. The distinction between a state of consciousness and one of nonsciousness could be due to (though not exhaustively)
1) though the subject is conscious of what she is doing, she is not conscious of that fact that she is conscious of what she is doing. A state of consciousness without an awareness of itself is actually nonsciousness.
2) The subject is aware of his overall experience, the sights, sounds, thoughts, emotions, sensations, etc; but does cannot discern whether or not he is dreaming, hallucinating, or if this is, indeed, reality. The ambiguity regarding the nature of reality deems this mental state as one of nonsciousness.
3) Dream consciousness, in general, can be said to be nonsciousness. There is awareness with less of the logical and rational restraint that is exercised during waking (sober) conscious experiences.
As said above, these are examples but by no means an exhaustive list of what type of mental phenomena may fall under the 'nonsciousness' category.
"The ballerina was keen to every muscle in her body, her form, each movement, the music, the audience...yet she was also 'in the zone,' unaware of herself completely. She was in a state of nonsciousness.