I have a light in the coop which usually keeps the temp 6-9 degrees warmer than the outside temp. The coop is insulated. My concern is a severe cold snap we are now entering which is exptected to last a week. Lows of -27 C (-17 F) and a daytime high of around -12 C (10 F). I'm tempted to leave the light on throughout the night as if I turn it off, the inside coop temp will most likely be very chilly. I don't like the idea of leaving a light on throughout the night (I like that they get proper dark....egg production is not a concern....the bird's comfort is foremost), however it seems the lesser of two evils so to speak. Any thoughts? Thanks.