I just now had an hour and a half of restful sleep.
But I was awake the whole time.
I'm not sure I can describe that sensation in a meaningful way.
But it sure is odd.
I'm not talking about insomnia or any sort of not-sleeping, I mean more like I lay down, relaxed, and my body stopped moving, and my mind was all like "aah. bed. soft. going to sleep..." but then just stayed that way, as if somebody left the switch on. It was pleasant. CNS activity a little above normal as well, had to take a deep breath once in a while to keep fully relaxed.