Artificial lighting and hen longevity

[RonP]

I wondered about these questions too. somewhere down the line I saw a reference on here to a book called the behavior biology of chickens (BBC), so I bought it. I read the thing cover to cover, it's fascinating and science based but not too technical.

Determined by a photocell for natural or artificial lighting, my coop AND run are lit up like a football stadium for 15 1/2 hours per day. Standard time, lights on at 5:30 am, off at 8pm. At 7:30 pm a second low level light bulb in coop and run is timed on for 1 hour, till 8:30 pm allowing any not settled prior, to settle in unstressed for the night. Then all lights off till the next morning.

365 days per year...

I do not cull. I have a mixed aged flock, one now in her 14th year... one in her 13th.
All seem healthy and happy. All molt regardless. 14 year old, a lone surviving bantam, gave me 8 eggs in 2018...

I would second the opinion, possible fact, that lighting has little to do with the health or longevity of the life of our birds.