What masters? All the ascended masters were well aware of consciousness. If you didnt have consciousness how are you even here? You wouldnt exist.
So in deep sleep, you don't exist?
In a way you are perfectly correct, what you think you are is not there in deep sleep. Yet, what you actually are IS there, for otherwise an alarm clock or outside noise wouldn't wake us.
It is dangerous to only look at a particular state of experiencing, all the three should be looked into. Deep sleep, dreaming, and waking, through each of these, what you are is constant.
This is why I push so much for the dropping of belief as such, where are your beliefs in dream or deep sleep? Where is your family or anything of your life in deep sleep? There is simply nothing there, yet still there is something, you remain.
Truth cannot be constrained to a belief, for the beliefs are only there in waking state. This is why dreams can become so absurd, they are not constrained, you need not obey gravity, you need not comply with time or anything else, you are beyond all of these, but the waking state is like a collective dream, only that which we as a society or community accept as feasible can actually arise.
Still, in deep sleep - something all genuine seekers need to understand - none of this is there, consciousness itself isn't there. Awareness is the only thing still functioning in this state, but we cannot be conscious of it because consciousness isn't there.
If we can be without consciousness, consciousness cannot be what we are.