I've been using a 100 watt bulb to keep the water from freezing in the coop and to add a little extra warmth. We've been between 5 and 20 for the last 2 weeks with snow on the ground and lots of wind. It's finally supposed to warm up next week to a balmy 40 and I won't need the extra heat anymore. Will it mess up their internal clocks if I turn off the light? Thanks for the help, this is my 1st winter with chickens.