The distinctions of waking state, dream state, and sleep state (viswa, taijasa, and prajna) are but appearances imposed on the Atma; that is to say, the Atma continues the same, unaffected by the waking, dreaming, and deep- sleep stages of man’s existence. This Atma and the Atma that one refers to as “I” are basically the same. The “I” or the Atma swims like a fish in the river, paying no regard to this bank or that, though the waters are limited and guided by them.
In deep sleep, all the impulses (vasanas) are suspended; though they still persist, they are not manifest or active. In the dream state, one follows the impulses and wins satisfaction in the process.
All the manifold pulls and attractions of the sensory world, which impel one toward the surrounding objects, are born during the waking and dream stages. The mind is full of agitations, and these are the fertile fields where the impulses grow, multiply, and strike root. As a matter of fact, it is the agitating mind that causes creation (srishti) and that is behind all creation.
However, there is a fourth stage that is distinct from these three: it is named thuriya(Transcend the mind and senses) ! This stage cannot be described by words or even imagined by the mind, for it is beyond both intellect (buddhi) and mind (manas). The experience is inadequately described as peace, grace, and oneness (santham, sivam, a-dwaithama); that is all. The psychological distress are stilled, so there is no more intellect. It is the victory of the mind, its rejection, the thoughtless stage.
What a victory it is! For in deep sleep the mind is latent; while dreaming, the mind is restless with agitations; and in the waking stage it is active and motivating. In all three stages, truth remains unknown. The objective world is but a delusion of the agitated mind, the superimposition on the rope of a nonexistent snake. The world is not born, nor does it die. It is born when you are ignorant and dies when you become wise. – “Mandukya Upanishad“.