I am happy for you that your chickens are doing well. I was under the impression from you post that you were asking it they would be fine without a heat lamp. You did not say you were using a lower wattage bulb.
If that was your question what I would agree that they would be fine at that...
I have always used a normal light bulb and have NEVER had any feather picking or any other problems.
Why don't you just move the brooder to a different room then you won't see the light at night. The warmth is the most important thing at NIGHT not in the day, as this is the time when they...
Use the normal household light bulb. They don't care about the light and dark and will just sleep when they are tired. Its better to do that than chance that they get too cold......and then sick.