So our chicks are about 6 weeks old and are in their coop. I'm still using a 150w heat lamp because if I turn it off they all squish together like they're cold. Temps at night are 50's these passed couple of weeks. We have 8 chicks. I feel like keeping the lamp on for them at night is going to mess with them. I do turn it off first thing in the morning. Is it ok to keep the lamp on at night for a few more weeks??