I added some light the first year. Will never do it again. I've had six hatchery girls die from internal laying and I have two more who are suffering from it now and will probably die. Artificial lighting pushes their bodies to keep on when they'd naturally slow down or take a break. If you have a commercial egg business, that's what you'd do, but I really believe that for backyard flocks, it's best to allow their natural rhythms to prevail.
Unfortunately, hatchery stock, especially the most common hatchery layer breeds, are bred to keep on laying no matter what. My girls didnt even break for their molts, so that molting period was a long, drawn out one for many of them. If they stop laying, their bodies can use the protein, vitamins and minerals to grow back their feathers faster.