Usually unconsciousness is related to aspects that we do not have cognizance of. But it has more to it. Most us to do not know much about our body or its functioning. We are not aware of various psychological and physiological functions that occur in us. However we do know the effect of these functions on our consciousness. The two states of our consciousness are the awake state and the sleep state. The sleep state brings us into partial consciousness state called dream in us and near zero conscious state called Deep Sleep. The dream state exhausts some of the superficial impressions on mind before the mind goes to quiescent state. But this quiescent state is temporary and it becomes active again at the level of unconsciousness when it returns to either dream state or awake state.
However what prevents us in not being aware during this unconsciousness, is a mystery. This is solved only when the mind's impressions are dissolved and intuitive mind develops.
Most seers who seem to have mastered consciousness by various techniques reveal that it is possible to develop the awareness of one self and there by reduce the effects of these unconsciousness.
When such awareness improves, we go into states of higher consciousness. Mind functions less out of memory and more out of intuition in these states. The Real Awakening is when the consciousness is fully aware and the unconsciousness decreases to nil.
What happens to the mind in such a state is that it reaches a state of perfect rest while it is active; It is then illumined to the level of a Perfect Man or The Mind.
A lot of these statements are from the domain that is outside the range of normal human mind and so language is limited in its expression. More research and development of psychology is required here.
What exactly do you mean by unconsciousness, like taking things in without knowing it, or being asleep/knocked out. If you mean the first one, then we wouldn't realize as many things, I guess. If it's the second one, then that may mean we would sleep less maybe. I'm not too sure