Waking, dreaming and deep sleep are separate? I am separate no you are separate from them but they are not separate from you. All universes physical universe and subtle universes and the causal seed universe all of these appear in one consciousness that is Brahman. Not one day is to exceed you by one millimeter or one millisecond nah tadu nah taitikaracharNo one can exceed you it's like saying if all the ornaments are made by made of gold so you can say Satsmin, Lokka, Shrita the universes are setting you they float in you like dreams.
Swami Sarvapriyananda teaches the Katha Upanishad, one of India's most revered texts which is also a part of the Vedas. It is a collection of philosophical poems representing a conversation between the sage Naciketas and Yama (god of death). They discuss the nature of Atman, Brahman and Moksha(liberation).