There are two schools of thought if you read online about this. One is that this is very annoying to the chickens, having a light in their eyes all night. I can understand that. I don't like to sleep with the light on, but I do fall asleep with the light on often. Then I have read in a chicken keeping magazine I was looking at while waiting in line at Lowes one day that basically said you might as well turn the lights on because chickens are usually eaten by predators before their end of egg laying life expectancy. I have found this to be the case for me.
So as our egg supply has dwindled and the prime egg using holidays are approaching I have decided to turn on my brooder light. This year however, I am using an LED. So there is not much heat being produced out there. I also have a light timer that has a photocell. It comes on at dark and I have it set for 4 hours. I am hoping this helps in the laying process. The packaging says the bulb uses $0.66 per year when used 3 hours per day. I will be using less than half of that so it isn't a large cost for eggs. I am also hoping that I can get the two chickens who have not laid an egg yet since they have hatched to lay. One is our Americauna and I would like to know if we will be getting blue eggs or green eggs from her. At first when I turned the light on all the chickens quickly turned their back to the light so I was a bit concerned. Quickly however, they turned around and started walking around. Some even went to the feeder and ate. I don't feel too bad that the light will be on until 9. They will still be getting lots of dark time.