We have added light in the evening, light in the morning, and light both morning and evening.
Without a doubt, we get more eggs just adding light in the morning. It seems that the light in the morning wakes them up and gets them moving and eating early, but light at night doesn't really do much for them. They still went to bed at the same time, whether there was light in the evening or not.
We have our light on a timer to come on at 4am and go off at 8am, which is dawn this time of year. They only need that bit of light, since the rest of the time it's daylight and that counts toward those 14 hours of light.
I strongly recommend against light all night. Every animal needs a dark period. Without it, it's a source of stress, can cause pecking, and might even decrease laying. My family has a largeish dairy farm, and there's a lot of research that shows that cows must have a dark period to reduce stress and give more milk. It's a pain to the humans, who need to do the night work with headlamps, but the cows get their dark.
We are getting 41-48 eggs a day from 50+ hens (I don't know exactly how many)
