mine too....There is a wall with a people door (and a pop door in it) between "coop" and "run." It's only 6 feet high, so there is some light through there...but only when it's really daylight. I have been shutting the big door at night (and sometimes all day) and leaving the chicken door open, to keep the breezes down. It's pretty dark in the coop, once the sun starts going down. There are some tall trees across the street in the neighbors yards and behind that screen the sun before it's actually down. (This is Maine...trees, trees, and more trees!)
Great thought, though. I would love to get a camera in there & see just what they are doing in the night. It also may be happening during their "nap" times. They like to roost & doze in the afternoons, too.