। ॥ १३ ॥
In plain words
In deep sleep the body and everything that comes with it are gone — and you are still there, witnessing their absence. Your very nature is self-experience; nothing else exists that could light you up.
Close to the Sanskrit
In sleep, even in the absence of the body and the rest, you are the witness of them; since, because of being of the nature of self-experience, there exists no other illuminator of that.