Yes. Chick embryos respond to UV light. They orient to it. It is important that the embryos don't stick to the inside of the egg. Turning the eggs helps prevent this. Leaving your eggs in a darkish environment may slow up the embryos repositioning.The eggs are fresh, so I'll keep my fingers crossed, and give it a good klucking try! By overhead light, do you mean to keep them in a darkened room? I'm not sure what you mean. I am hatching these in my house. And thanks for responding so quickly.