[Advaita-l] waking, dreaming, sleeping, as mutually supportive

[Shrinivas Gadkari]

Namaste,
 
Here is my understanding in brief:
 
Sleep is the base state. This is the state of akSara puruSa.
From sleep ones "wakes" up into either "dream" state or "awake"
state. Both these constitute the state of kSara puruSa.
 
As you have rightly pointed out "dream" state plays an 
important part in sAdhanA.
Outward description of of any upAsanA highlights the inter-play
between "dream" and "awake" state. 
 
You might want to inquire if "sleep" state has a role in sAdhanA.
(mahA viSNu sleeping on a snake may be some indirect reference
on this front.)
And then what about fourth state.
 
I am not aware of any scripture which talks openly and explicitly on
these issues. 
 
Other than mANDukya other text that treats this topic somewhat 
more deeply is the last chapter of chandogya (prajApati's intruction to 
indra). Some material can also be found in yAjnavalkya discourse to 
janaka in bRhadAraNyaka (4th chapter - I think).
 
Regards,
Shrinivas