A duete vedante is done in the waking state, in full alertness of mind when we can inquire clearly. It uses sleep as a powerful tool for understanding who we are or what consciousness truly is. All three experiences you talk about - dissociating from the world, body mind and being knocked off your normal way functioning -- are all part of the mind.
Q&A session lead by Swami Sarvapriyananda at the Vedanta Society of New York on June 5th, 2022. List of questions with timestamps:
00:00 - Intro
01:32 - How is it that the self is in all beings from the chit (consciousness) perspective?
18:37 - Where is my consciousness when I am sleeping? Can I use sleep as a spiritual practice?
26:55 - Will a realized person retain their individuality after enlightenment?
40:38 - Why do we call this world false?
55:53 - What does Sri Ramakrishna mean by going into the black water (in reference to samadhi)?
01:00:30 - If we want to take up a life of renunciation, what practices should be followed?