pure awareness or pure consciousness

From the time I started reading spiritual books in English after college, I have been reading and hearing the words ‘pure consciousness’ and pure awareness’ too often, but never doubted what the words meant, accepting the obvious meaning that came to my mind, without an iota of doubt. But now I am confused.
Of course I know that I am aware of something. But do I know any awareness without that something? The legendary smile without a cat?(apologies to Louis Carroll). Can awareness stand independent of the thing I am aware of? I don’t find it possible. I can be aware of nothing in particular. That would mean that I am aware of everything in an expansive way, in an expansive mood.
When I close my eyes I am not aware of any impression of things in the outside world that may be approaching me towards my eyes. But the blank screen, the colourful screen before my closed eyes, I am aware of. And I am aware of all the noises, the touch of the breeze from the fan, etc. And I am also aware of all things that can come out of my memory. But if I do not divert my attention towards any of them I may not be aware of them at the particular moment. In any particular moment my attention stays with some object of which I am at that time aware of. And what is that attention? I notice that it is focused awareness.
If the body and mind is in alert attention throughout, can you say that it is in pure awareness? Then the nervous system as a whole is awake and alert. No thought is present in the mind. Can you call it pure awareness?. I don’t think so. The state is something temporary, and limited to the body and mind. Then what is the nature of pure awareness? It must be something behind the alertness, making the alertness possible. It must be the one which illumines me- makes me tick, pulsate - and all that around me up to all space. Is that right?
Throughout the waking state attention is every moment on something or other. I therefore find that awareness and attention are existent along with the object of awareness. Therefore, ‘pure awareness’ or pure consciousness is something other than awareness, perhaps the power that makes awareness possible. A new word has to be coined. Existing words have other meanings and may be misunderstood and ‘misused’.
Another question is what happens in deep sleep when there are no object present? Awareness of ‘nothing? Where lays pure awareness then? Keeps the body alive? Why not try to ‘feel’ the awareness in sleep? That can perhaps solve the problem. Is +80 too late to try?