Does anyone have any thoughts about how many nights in a row you can keep the lights on all night in the coop? I use incandescent bulbs to add some heat in the early hours of the night in winter. Very occasionally it's so cold I leave it on all night. I think it makes them a little weird not having any darkness. I've never done it for more than one night in a row before but this winter is unusually cold. Does this cause any problems generally? Thanks for the advice, as always.