I see in Storey's Guide to Raising Chickens they talk about using artificial light to lengthen the day to keep the hens laying eggs as the days get shorter. On page 126 of my copy of the book, they also show a table giving the maximum height of the lights above the birds for various wattage bulbs, ages of birds, with or without reflectors, etc. My question is, WHY? But the book doesn't say. It suggests that maybe shadows aren't such a good thing for the birds to see, but there's no explicit explanation for all these hard and fast rules about the heights of the lights. Can anyone help illuminate this issue for me?