They say 14 hours is necessary for egg production. I give mine at least 16 hours, and it keeps them laying all winter long. Yep, they will start slowing down now with the daylight hours getting shorter. Here it's only light about 12 hours now, so they need more light to keep laying. I just put lights on my quail, who were slowing down, and left them on 24 hours a day for the first 3 day, then went to the timer, and my egg production has almost doubled in 5 days. It's worth a try if you want your birds to keep laying. I figure with the cost of feed, I need to keep them producing, even if we just eat the eggs.