Every night my chicks all pile up and sleep right near the coop door. I leave a dim light on for them in the barn that is not to bright because I thought they were scared of the dark. They are 7 weeks old. Why do they all sleep by the door? The go on the roosts during the daytime but not at night. What can I do to get them to stop piling on top of each other by the door at night? Why do they do this?