I live in Northern California, and it's been between 34-40 degrees at night. I have five hens in a 3x4x4 coop. They are 13-14 weeks old and fully feathered. Can they sleep without supplemental heat/light now? Do I need to wean them or can I quit the light cold ...ahem...chicken? They have been sleeping with a 75 watt infared bulb. Thanks for your help!