I don't know if messing with their sleeping pattern will impact their health, but keeping a heat lamp on for a month or so could. What happens when you take the heat away and they haven't had a chance to grow the extra feathers they need to keep warm? Or if your power goes out and suddenly they go from a warm coop to a cold one? They will be just fine without supplemental heat. If the light is a new thing, it could have caused the lack of eggs, or it may have just been an off day for them. Do your chickens a favor and get rid of the heat lamp. I do know what I'm talking about - I live in MN, and it gets into the -20's and -30's here in the winter and my chickens have survived just fine.This is my first winter with my 4 girls and i have installed a 125watt heat lamp at night since it has now dropped to below 0. My rule of thumb had been anything below 10 degrees to give them heat at night. However my concern is that their sleeping pattern is off. Last night was the first night with their heat lamp, and today I noticed they spent the majority of time in their house - which I thought was because we are experiencing a cold snap. However tonight when I went to check on them I noticed they were wide-awake with the heat lamp on, so now I am wondering if they were actually sleeping today during the day while their house was darker and they're staying awake at night with the light on. Also we did not get any eggs today which was unusual as well so I'm wondering if their sleeping pattern is getting really messed up with the heat lamp on at night..... Any thoughts? Will messing with their sleeping pattern for a month or so impact their health?