Not to pick a fight, but most of the statements of the previous two posts are not backed up by any research conducted by the top agricultural universities in the U.S. or Canada. That research says artificial lighting does the hens no harm, provided they get proper nutrition and are allowed to molt every 12-18 months. If you want to get specific about what is and is not natural, then you should let your hen lay a clutch of eggs and then allow her to hatch them instead of tricking her into laying more eggs by taking them for yourself. By the way, most chicken breeds originated from junglefowl on the Indian subcontinent, so it can be argued that humans have bred (tricked) them to sustain cold, dark winters in Canada in the first place, so who's interferring now? Chickens stop laying in winter because in the natural world, there is less food available for survival - not an issue for our chickens.
Bottom line: chicken keeping and breeding
is human interference. The arguement should be what is responsible and irresponsible interference - for me, I rely on actual scientific research to determine that. That being said, every individual has the responsibility to do what they feel is best for their chickens. I agree that up in Canada, allowing the hens to take a break due to severe cold may be the way to go. Here where I am, we have yet to get below freezing, and my hens are happy, healthy, and laying.
For those who would like futher education on small flock health care, I found this link to a manual produced by the Canadian government:
http://www.agf.gov.bc.ca/ahc/poultry/small_flock_manual.pdf