I get up with my chickens and they go to bed before me. They get to free range at least 3 hours a day - the bugs in our yard are having a tough winter, but the chickens are happy, spoiled, and laying. This issue has been studied extensively. A hen will never "run out of eggs", they will quit laying due to old age long before that. They are born with hundreds of thousands of ova which would take decades for them to lay. Extra lighting in the winter does them no harm if they get proper nutrition, but they are supposed to be allowed to molt every 12-18 months. Next year I will let them molt, which is when they are supposed to.
By the way, speaking of artificial conditions, most chickens are descended from junglefowl from the Indian subcontinent and have no business spending cold, dark winters up in Canada, but they make do (actually do-do and that's about it). Here is a link to a small flock poultry health manual from the Canadian government:
Don't take my word for any of this; you can easily research it for yourself on the Internet.
Edited by CovertChickOps - 12/27/12 at 10:29am