They can see OK in low light...erratically changing the time light is on in the coop could screw up their laying cycle.No it's not on all night, they would never sleep.
I'm experimenting with different times. Work location and schedule is changing. Right now it's on longer at night. They were fully active last night until 9pm. We had decent weather and that will change soon enough.
So this morning I put the light on in the coop and not in the run. The barred rock came out and was scratching around in the dark without issue. Caught me off guard because everyone says they can't see in the dark and she was having a good old time.