Our son just finished his science fair project. He tracked the effects the hours of light had on the egg production for our hen flock. What we learned is that not only is it important to have the right amount of light, the right type of light had even more of an effect. The sweet spot was a warm fluorescent shop light for 14 hours. If you use a cool white bulb.....................no eggs. Once we changed to the warm bulbs it was like flipping a switch on the hens' ovaries.