Non-dualistic Hindu philosophers talk of Turiya, or a 4th state of consciousness. According to the Shiva Sutras
of Vasugupta: Turiya is the fourth state of consciousness beyond the states of waking, dreaming and deep sleep. Turiya strings together those three states. It is the Metaphysical Consciousness distinct from the psychological or empirical self. It is the Saksi or witnessing consciousness. And it is the transcendental Self.
Many years back, while going through a phase of deep meditative experiences, I'd experienced a prolonged state of being vividly and lucidly aware and conscious while in deep sleep, which was so out of the ordinary and yet so real that I felt it must correspond to this state of Turiya.
However, the question that continued to bother me was what happens when one is in the state of deep sleep without awareness, which is the normal, day-to-day experience of most of us. The following explanation offered by Sri Ramana Maharshi, the great mystic, did nothing to answer the question:
Bhagavan: So there is a continuity in the sleep and the waking states. What is that continuity? It is only the state of pure being.
There is a difference in the two states. What is that difference? The incidents, namely, the body, the world and the objects appear in the waking state but they disappear in sleep.
Question: But I am not aware in my sleep.
Bhagavan: True, there is no awareness of the body or of the world. But you must exist in your sleep in order to say now ‘I was not aware in my sleep’. Who says so now? It is the wakeful person. The sleeper cannot say so. That is to say, the individual who is now identifying the Self with the body says that such awareness did not exist in sleep.
Explanations notwithstanding, it seemed to me that one could equate the mind with the self, and that both cease to exist when one is deep sleep or in a faint. I'd experienced episodes where I'd passed out due to not having eaten for too long - the experience is clearly one of a machine shutting off, and you have no recollection of anything, existence or otherwise, till sufficient blood flow resumes to the brain and you come to. (The deep sleep experience is typically preceded and succeeded by the dream state, and is therefore harder to isolate.) This mechanistic explanation seemed to suffice and was at odds with the position taken by Advaita Vedanta.
Early in 2017, this question about the validity of the Turiya state was nagging me to no small degree. Was there really a continuity of self across waking, dream and deep sleep, when I'd personally experienced a clear discontinuity of self on the occasion of these fainting spells? It was in these circumstances that I had a most unusual dream experience during a business trip to India that seemed to provide a clue.
In the dream, I was lying in an operating theater at a hospital about to undergo a medical procedure. The doctor asked me to hold my breath as long as I could, and with a force of effort and no small amount of pride, I held my breath for 10, 20, 30, 40, 50,...seconds, and then suddenly, due to a lack of oxygen, I passed out. Yes, I passed out in my dream, and as would be the case with a "real" fainting episode, there was a complete absence of awareness. I was a complete blank. When I came to, the doctor had apparently completed whatever medical procedure it was while I was unconscious. And then, I woke up.
Analyzing the entire experience, I could see that the "real" me (who is writing this post) had existed throughout the dream experience, while the "dream" me had transitioned within the dream from waking state to unconsciousness (faint or deep sleep) back to waking state. The real me was the "continuity that strung together these states" within the dream, and that could say "I was not aware while in deep sleep but was yet there."
Sometimes, it takes a dream to reveal the reality of things.
