Last year I had a small light on in the coop, to up egg production. Some people say it stresses them out, others don't worry about it. What do you say.
I've had lights in the coop for years. Never heard it was a problem until I joined BYC. Have yet to see any concrete information, that it is a problem. And my chickens are not stressed out.
Personally, unless it's light 24/7, I doubt it stresses them out, although being in the coop and awake that much longer might. After lots of reading and discussion, we decided not to provide additional light. Even though we only have 6, they still produce more than we need, so we figured we'd just let Mother Nature handle things