There are poultry mites and ticks that hide in cracks of the coop and only come out at night. To check for these, go out with a flashlight and check the inside of the coop and the hens. See if these critters are keeping your hens up at night.
The yellow-gold ones are California poppies and the blue ones are bachelor buttons. Both are wildflowers here and are blooming in my garden as we speak. :frow