Extra light is an unnecessarily touchy subject. Some people get really upset at even the mention of it.
We need to remember that chickens were initially tropical birds, from the equator, getting roughly 12 hours of day and 12 hours of night. They were moved to the cold north by us. They have been bred for many centuries for our use to do what we want them to do. There is nothing natural about a modern chicken, and they wouldn't and don't survive well in nature. Wild chickens don't lay 275 eggs a year. We have created this. I do believe we should respect them, and treat them well, but they are a human creation, and within bounds, it's fine to stimulate them to help us out.
People who live in the far north get very few hours of sunlight per day. Far fewer than those in the south. If it's dark a chicken can't eat, and if a chicken can't eat for 16-18 hours, it's probably not going to have extra reserves to put into making eggs, particularly if it also has to keep itself warm.
Chickens also have a set number of eggs that they will produce. Some do most of it in 18 months. Others do it over a period of several years. Of course, if a chicken dies or is killed before she lays all of her eggs, you've lost that laying potential.
There is no harm in leaving the lights off, so that your older hens get a break and go through their natural molt. You may find that some of the pullets start laying anyway. You could even wait until the molt is over or underway to lengthen the days to encourage egg laying in the younger birds. Once molting is triggered, it seems to run its course. Just make changes gradually so you don't shock their systems. What you don't want to do is try to starve the older birds into molting, which is the cruel practice used by some egg factories.
I lit mine last winter, with no ill effects. I've decided not to light them this winter to give the older hens a long rest period, even though the youngsters are just coming into lay. I'll be happy for any eggs I get over the winter, but really don't expect all that many until next spring. My 1.5 year olds are in fulllll molt right now. The spring chicks are just starting to lay.
To me, waking them up a bit early, or keeping them up a bit late is far less cruel than having to support factory farming by buying eggs at the store.
