Well. Bingo. You've got northern fowl mites very likely. They are driving your chickens crazy, and quite possibly slowing ruining their health. They will feed on the chickens' during the night, and it makes them anemic, setting them up for all kinds of health issues, acute stress being the least...
Have you checked your coop for mites? You need to do it at night. Look for tiny bugs running up the legs of your chickens. Run a damp paper towel over the perches. If it comes away with red smears, you will know why your chickens have been so stressed out at night.
Other than that, monitor this...