I've noticed something odd about the lighting in mines - it's sometimes easier to see, sometimes harder. In particular, the light from my hearth seems to reach farther at night when the moon is full, than it does during the day.
I almost hate to report this, since odds are the moon effect is unintended, and the normal fall-over-things visibility would happen all the time if this were fixed.
So while I'm mentioning this strange effect, I'll once again put in a plea for better lighting in mines - on behalf of all of us who live and store our stuff in them.