Their own body maintenance takes precedence for the nutrients that could have gone into eggs otherwise, Ann. They need the protein to regrow feathers.
Sometimes they can produce a few eggs while molting. In mid September, my hens, except for one, decided to lose feathers. The odd one tried to go broody.
The molting hens managed to lay a few eggs thru their molt. (Molting usually takes a hen at least a month.) After some convincing, the broody gave up setting on either infertile eggs or an empty nest. And, she began to lay again.
Soon, I had more eggs than I knew what to do with until Ms. Olivia Broody decided it was time to molt. Now they've all shut down.
I began to add some light during a real cold spell in early October. They are now up to 14 hours of light and that's as far as I'm going to go. There are feathers all over the coop so I'm not expecting much from Olivia but the others should be back in gear.
They are less photosensitive as they grow older, as I understand it. However, there are other factors than light to egg production and young pullets are more driven to lay. About the only thing we can do is make sure that they have ample nutritious food and the time to eat it. Having a light on in the coop is part of that scheme, too. In December, my chickens would have less than 8 hours out of every 24 to find their food if they only had sunlight. Having a light in the coop for the hens is just a part of the price I pay for having chickens so far north. That's the way I see it, anyway.
Steve