Here, also, there are universal indicators that offer a convincing conclusion of sleep—two, in fact. First is the loss of external awareness—you stop perceiving the outside world. You are no longer conscious of all that surrounds you, at least not explicitly. In actual fact, your ears are still “hearing”; your eyes, though closed, are still capable of “seeing.” This is similarly true for the other sensory organs of the nose (smell), the tongue (taste), and the skin (touch).
