Consciousness is untouched by the happenings in waking, dreaming and deep sleep. The word used in sanscrit is pracashaka. It's simply like the light here which illumines everything. Prakashaka is not affected by which it Illumines. That which is an appearance cannot affect that which is real. Even the so called real world of the waking, or the dream world, or the deep sleep darkness are all appearances.
Swami Sarvapriyananda speaks on “The Essence of All Vedanta” at the Vedanta Society of New York - April 8, 2018 | Vedanta NY