So I have a Destial headcannon that Cas watches Dean sleep, but not in like the "he's so peaceful when he's sleeping" way more so in the "Please dont stop breathing" way.
At first it was just listening for his breathing even of he was thousandsof miles away he would still check for it every now and then.
It started after he pulled Dean from hell. He could rationalize it as making sure his charge was safe.
Then Dean died, and suddenly it wasn't enough anymore. He told himself he was just being vigilant, and would pop in the room every couple of hours just to check.
Then even that wasn't enough to calm his unease, and it soon got to the point of Cas needing to watch Dean's chest slowly rise and fall in the same rythmic pattern he had memorized, and if Dean even slightly strays from that pattern he panics.
He has shaken Dean awake before simply because he was breathing weirdly in his sleep after his ribs broke from a hunt.
The first night he did it though, he didn't wait for Dean to fall asleep, and Dean was creeped out by the angle just sitting there stairing at him from across the room.
After awhile of him just staring Dean finally told Cas to atleast get a book or do something other than just stare. Now Cas sits in bed with him and reads, or runs his hands along Deans back or arm until the man is asleep.
