Your experiences during "conscious sleep" almost exactly match many phenomenon described by meditators and that of ego/mind death as described by UG Krishnamurti. On the experience of "being flattened":
>“When I lie down and close my eyes, the outside world completely disappears, and there is only the awareness of what is happening inside, the lub-dub of the heart. The whole human being is reduced to just this awareness of the heartbeat (laughs), and then suddenly even that is gone. I don’t want to use the word ‘samadhi’. Every time it happens, it happens in a different way. And then sometimes there is a flash of light and everything is gone, it is totally blank; perhaps that is pure consciousness. This is not a vision. You know I am very sceptical. But I can’t compare this with anything. And I don’t rush out to refer to some book to find out what it could be. I’ll have to discover it myself and this is a moment-to-moment business.”
>“This is perhaps called samadhi, going into samadhi. Say you are lying down on the bed and because there is nothing else to do, you watch your body. Actually you are not aware of your total body when you lie down, only those spots of the body that touch the bed. And when this happens, after a while, all of a sudden some kind of a searchlight is thrown on this point (head?)—this is some kind of awareness, not a vision—this is like a searchlight from the top like you find at airports, and it moves from one point to another, slowly, back and forth”
>“Yesterday, I was lying on the bed and the body disappeared. There was awareness of only the head. (This was unrelated to the previous state, yet a similar one. But how it comes into being every time is different). And then all of a sudden the awareness disappeared from my head and there was only the bed. When you are in this state, you can’t do anything. But, later, I was narrating this to Valentine. It is like the Mickey Mouse story—what you see in the Tom & Jerry cartoon film. Something hard and heavy falls on the cat and the cat becomes flat... When I woke up, I thought, ‘What is this? My body is so flat!’ At the time you can’t do anything, only later the mind comes in and tries to understand but it cannot—it can only speculate, imagine, which shows that the trace of the mind is still there. It comes but gets no answer.”