Well, my SIGHTINGS have always been in enough daylight to SEE. Funny how that works, right?
I've had a couple (+) instances where camp was entered or approached. All of those have been in full darkness .. qualified. They were in the dark part of nights where there was 3 hours or more of darkness even if there was a full or near full moon for the rest of the night. It's a 100% hit rate for me. I have bumped into them wandering around on full moon nights but only when I was down in a shadow where there was no light .. deep canyon or the like.
My theory is they can see us and they think, incorrectly, that we can see them much better in darkness than we really can. (Kinda accounts for the nocturnal tree peeker at Bumping Lake, right?)