Sleep is a complex process. Consciousness instead of folding and being within identifies itself with a different state of being. There are 5 such states
Awake : we know what it is but what is it that consciousness anchors to that causes awareness of body and forgetting self ?
Sleep : here consciousness forgets self and the body but is aware of a cinematic projection coming from chitta. This of course is more complex and a yogi has the ability to pick not the chitta but to go into savikalpa samadhi. This technique has to be learnt, mastered with the blessings of a true guru. There are ways to differentiate sleep and samadhi visions which I have written elsewhere
Sushupti: this is a state where neither there are visions of dream or awareness of body but a layer that remains incognito.
The other 2 states should not be revealed or discussed openly since it is given by a guru and not for the general casual reader
Who is a casual reader ? Someone who keeps surfing the web, reading things collecting the dirt of bookish wisdom rather than going straight for the experience and in search for a guru. There must be intense passion for God. Then and then alone does he permit the divine power to descend
Bhavin