No one gets out of deep slumber with the feeling that he did not exist during that period, nor even out of dream-filled sleep when he may have assumed a different identity. Both states are looked on as different but not as annihilatory: so deep sleep shows that consciousness can exist despite the person's ignorance that it is an entity by itself apart from him and his body, thoughts or emotions.

-- Notebooks Category 19: The Reign of Relativity > Chapter 3: The States of Consciousness > # 136