The three states of consciousness — and the "fourth"

The Mandukya Upanishad is short — a few dozen lines — and entirely devoted to one teaching: a map of consciousness in three ordinary states, plus a fourth that isn't quite like the other three. The three ordinary states are familiar to everyone, every day. Waking (jagrat) is the state where you experience an external world through the senses — this is the "self" most people mean when they say "me," the one having a day, interacting with other people and objects. Dreaming (svapna) is the state where the mind generates an entire internal world with no external senses involved — a self still appears to exist inside the dream, experiencing a world, but that world is made entirely of mind. Deep, dreamless sleep (sushupti) is different again: no external world, no internal dream-world, no objects of experience at all — and yet it isn't experienced as absence or suffering. People wake from deep sleep and describe it as restful, undisturbed, even though nothing was "experienced" in the usual sense. Each of these three has a different relationship between a self and objects — external objects, internal (dream) objects, or no objects. The Mandukya's move is to ask: what is common to all three, present in each but identical with none of them, since it doesn't come and go the way waking, dreaming, and sleep come and go? That constant is called turiya, "the fourth" — though the texts are careful to say it isn't really a fourth state alongside the other three, the way a fourth room might sit alongside three others. It's better described as the awareness in which all three states arise and pass, the witnessing presence that's there whether you're awake, dreaming, or deeply asleep, since something in you clearly persists across all three (you know you slept, you know you dreamed, even though "you" as the waking personality wasn't there to observe it happening). Advaita identifies this constant, background awareness with Atman — the same "you" the rest of the tradition keeps pointing back to, here approached through the structure of ordinary consciousness itself rather than through argument.