I am a new chicken raiser, I bought 18 pullets iso browns. first 6weeks I kept them in a very large box with a heat lamp then when they got big enough I moved them to a large pen totally enclosed with a hen house that is insulated with a light on 24 hrs a day and plenty of hay and roosting shelves. They are all doing good and at 6 mnths or so they began laying. so they lay eggs in henhouse, but at night they sleep in the enclosed pen. it is starting to get cold and then are still sleeping all together in pen, not the warm hen house. But they always lay in the hen house......suggestions???