In this non-appearing, one single thing shows itself. But it does not show itself to others, and in this precise sense it does not appear. It shows itself to itself and, even better, in accordance with the distinction posited, it shows itself in itself, it appears to itself in that minute and intimate interstice between self and self, there where self is self. That is why its philosophical expression is indeed this "I am," this ego sum that Descartes does not doubt is independent of whether or not I sleep and of whether or not everything I perceive is on the order of dream.
"I am," however, heard murmured by the unconsciousness of a dreamer, testifies less to an "I" strictly conceived than to a "self" simply withdrawn into self, out of reach of any questioning and of any representation. Murmured by unconsciousness, "I am" becomes unintelligible; it is a kind of grunt or sigh that escapes from barely parted lips. It is a preverbal stream that deposits on the pillow a barely visible trace, as if a little saliva had leaked out of that sleeping mouth.
The man or woman whose mouth thus mumbles a confused attestation of existence is no longer "I" and is not truly "self": but beyond the two, or simply set apart, indifferent to any kind of ipseity; he or she is in self in the sense of the thing in itself that Kant made famous, not without risking more than one misunderstanding. The thing in itself is nothing other than the thing in itself, but withdrawn from any relation with a subject of its perception or with an agent of its manipulation, from all phenomenality, the sleeping thing at rest, sheltered from knowledge, techniques, and arts of all kinds, exempt from judgments and prospects. The thing not measured, not measurable, the thing concentrated in its indeterminate and non-appearing thingness.
The sleeping self is the self of the thing in itself: a self that cannot even distinguish itself from what is not "self," a self without self, in a way, but that finds or touches in this being-without-self its most genuine autonomous existence. Further, this existence should rightly be called absolute: ab-solutum, it is detachment from everything, it is that from which every link, every relation, every connection or composition, has been dissolved and excluded. It is that which essentially comes undone, detaches itself and releases itself even from any relation with its own detachment. The thing in itself knows nothing about other things, and everything that appears to it or makes itself felt to it comes only from itself, comes to it in self from self, without any distance to travel, without any performance to present.
There is no representation, there is barely presentation, barely presence. The presence of the sleeper is the presence of an absence, the thing in itself is a thing of no-thing. Mass, though, which is massive, massed, rolled, curled around this self that exists by insisting on a nonexistence. Not, however, pushed or driven back into a stupefaction: on the contrary, rapt in fervor, in an adoration of the world where it opens its strange peace.
--J-L N, The Fall of Sleep [Tombe de sommeil]