Usually when people (including myself) have a micro-sleep (e.g. momentarily nodding-off while reading quietly) this is perceived as an absence, an interruption in the stream of consciousness, a jump-ahead in time with a chunk missing.
Indeed, people may not realize that they have been asleep unless told by an observer.
But sometimes I doze-off straight-into REM/ dreaming sleep; indeed alternate between being awake and aware of surroundings with being asleep and in dreams.
Eyes open, there is the world; eyes closed, in a dream.
So the micro-sleeps are associated with micro-dreams, or fragments of dreams.
(Dream-dozing can typically only happen if the person is lying down, or has their body and head supported to some extent - such as resting in an armchair; since dreaming sleep is associated with muscle relaxation which would otherwise cause the person to jerk-awake.)
My experience of this phenomenon of dream-dozing with micro-dreams is interesting.
It feels like flipping-between two ongoing realities, with time subjectively moving at the same rate in both waking and dreaming; but going at different rates when one state is compared with the other.
By ongoing realities, I mean that (of course) the real world is going-on even when I am not attending to it, so that when I awaken from a micro sleep things have moved-on in the real world: if I have been asleep of a second, then a second has gone past - obviously).
The same applied to the dream world: if I have been awake, then when I return to sleep, then time has passed in the dream world.
But if I have been awake for one second, then more than one second of subjective experience - indeed much more than one second, has passed in the dream world when I re-enter it.
And, conversely, what feels like some minutes of dream story can occur in a few seconds of awake time.
If awake time is taken as the calibration, then dream time moves 'faster' - in the sense that a lot more narrative happens in a dream during one second of awake time than vice versa.
Also, the dream world is narrative, a story; whereas the awake world may not be perceived as a story.
The micro-sleep is a slice of narrative; the micro-awakening may be simply an image - for example a static picture of the room where I am dozing.
So in the micro-sleep I am in a story, when I open my eyes, I merely see the wall and chair.
What this feels like is that dreams are stories going on all the time, without me being aware of them.
When I have a micro sleep I can sometimes dip-into a segment of this on-going dream narrative.
So I fall asleep and experience in dream what feels like quite a lot of some narrative, then wake-up and almost no time has passed; then fall asleep and rejoin the dream but the dream has moved on a lot while I was awake.
In general, dreaming seems to be like a process that is going on behind the scenes, mostly without awareness. Awareness of dreams seems like an non-essential optional extra.
Whatever it is that dreams are doing, apparently does not need our awareness (and indeed many people claim not to dream, or very seldom; and everyone rapidly forgets most of most dreams).
So if (if) it really was true that dreams are pre-cognitive in the kind of way tha JW Dunne and JB Priestley have said, and that JRR Tolkien and CS Lewis apparently believed, then much of this pre-cognition would have to be having effects without awareness, would be having unconscious effects.
If pre-cognition was real and had a purpose; that purpose would be unconscious, implicit, a background to our aware lives.