The Self, which is absolute bliss, is the witness of the three states of consciousness (i.e., the Self is common factor present in all three states). Three bodies are active in experiencing the outside world through the three facets of life, the state of waking (Jaagrat), the state of dream (Swapna), and the state of deep sleep (Sushupti). Even though the Aatmaa (ego, consciousness or Self) is the same in all states; but, due to material conditioning, we act differently in these states as though we in ourselves are three different entities.
In other words, the Infinite consciousness is one and the same, the Reality is one and the same, though it functions differently in the three planes of existence and, in these three states, it seems to gain three different sets of experiences. Accordingly, the waker in us seems to act different than the dreamer in us, and the ego manifesting through the sleeper in us seems to act different from both the waking and dream-state in us. The four Vedas describe the world of objects. They explain and expound three states of consciousness.
1. State of waking (Jaagrat)
The first state called waking-state-ego, results from the ego enjoying the expression of consciousness through the gross body. In the waking-state-ego, we are aware of our body, mind, and experiences gained in the external world of the sense-objects. To put it otherwise, in the waking-state the consciousness becomes dissipated through the mind and the sense organs in the external world of sense-objects and registers knowledge of them. That is all.
To put it otherwise, while awake, the only enjoy known to man is these five fields of the objects of the five cognitive senses; forms, taste, sounds, smells, and touches. Hence, conditioned consciousness (false ego) confounded itself with the frame of the body, seeing through the ignorance of its own True Nature, perceives a world of sense-objects, and thus deluded by its own false perceptions, experiences the waking-state. Our knowledge of the world-of-objects in this state is the sum total of our perceptions gathered through our senses.
2. The state of dream (Swapna)
The second field of consciousness, the dream-state-ego, results from the play of consciousness in the subtle body. When the same awareness playing in the outer world-objects withdraws and identifies itself with the subtle body, it creates a distinct personality called the dreamer, who has for its sphere of activity the world of dreams. In other words, the state of dreamer is created when the consciousness is withdrawn from the gross body and it fuctionts through the subtle body.
As the dreamer is unaware of the gross body, he functions in the world of dreams, because he is conscious only of the inner world of objects. The dream world is nothing but a mental creation of the dreamer himself. During the waking-state, the mind experiences the world of sense-objects and gathers impressions. During the dream-state, one part of the dreamer's mind observes these impressions in another portion of his own mind!
3. State of deep sleep (Sushupti).
In the third state, the deep-sleep-state-ego, the sleeper does not desire any sense-objects, nor does he see any dreams. It is the withdrawing of consciousness from the gross (waking) and subtle (dream) bodies and functioning through the causal body that creates the state of deep-sleep. In other words, this state takes place when we are conscious of neither body nor the mind, therefore it is a state of living in which usual instruments of cognition are closed down! Here the Self identifies Itself with the causal body which is made up of nescience. The only thing we experience in deep-sleep-state is utter ignorance or negativity; for there is neither form, nor sound, nor smell, nor taste, nor touch.
It illumines nothing in particular, except the one single idea: "nothingness". Here in the deep-sleep-state-ego, thus, the entire consciousness available in the human form is consolidated and conserved. As a result, there is no agitation in the mind, because none of the forces that create mental agitation and sorrows in the waking and dream states are present here.
Therefore, in this state of homogeneous solid mass of pure consciousness, the Jeeva experiences complete joy and bliss, by means of the subtle nescience. It is the gateway (cause) for the projection of consciousness into other two states of consciousness, the dream and the waking. For example, when the consciousness from the sleep-state is projected upwards, it illuminates the dream-state, and again, when the projection increases and come to the outer world, the same consciousness makes it possible for us to know the external world of sense-objects outside, in the waking-state-ego. The waking-state-ego and the dream-state-ego are conditioned by both cause and effect. Ignorance or non-apprehension of the Reality is the cause, and the resulting phenomenal world of names and forms is the effect. In the dream-state-ego, although we are unaware of the world of outer gross objects, but we are aware of the world of plurality or inner objects. The deep-state- ego is different than the waking and dream states in that it is conditioned by only the cause. Again, ignorance of the Self is the cause which gives rise to plurality, finitude, doubts, limitedness, and misunderstanding. There are no effects in the deep-sleep state as we are unaware of the multiple world of phenomenon.