If your coop gets some daylight, try turning it off and on during those times. It will allow the birds to adjust to the experience.
One-half of my coop has no daylight right now except what comes in thru a small chicken door. The light is on thru the day as you suggest.
When I first start using the light, I have a window to open so the light could be turned off. Getting a little cold here for opening that window during the daytime, now. I like to have the temps above freezing on that side altho' they can come outdoors whenever they want.
What time does it get light where you are? It starts to get light here between 6:30 and 7:00 and we have our light come on at 2:00 AM and go off at 7:00 AM. It has made a big difference in egg production.
I have mine timed to come on at 3:30 am and off at 7am. I am not bothering with an extension of light in the evening. This gives them 14 1/2 hours of light. In a couple weeks it will go on at 3am, but that's it.