How is it possible that we're able to view light through our eyelids, being awake compared to asleep?

I myself found it hard to come up with the details in order to explain this question. If you closed you eyes in a lighted room, you’d be able to “feel” the glow of the light source, correct? Your pupil is still able to see and sense the rays passing through the skin.

Why do you see complete darkness when you’re asleep? By that I mean waking up to nothing until your eyes had adjusted to the brightness. Unconsciously you see a blank wall of black before you wake up. Why do we see black?