A Theory About Molting Hens

So, now I have a new idea about why hens don’t lay eggs over the winter.  I had been thinking it was because they're molting; you know, a molting hen lays no eggs.  But, of course that can't be right.  This year, although only one of our hens molted, eight took the winter off.  Clearly, it's not the molting that matters.

My new theory is that it's not the molting, it's the daylight, and I have tested it, at least rudimentarily. This year, our girls stopped laying about 10 days before Thanksgiving.  That would be around November 15th, and they started laying again a couple of days ago, about January 24th. That would mean they stopped about 34 days before the shortest day of the year and started again about 34 days after. And there you have it.  It could be coincidence, of course, but more likely, it's the daylight that matters. I’ll be willing to bet my best layer cake on it next year.

As to the other odd thing about the winter lay-off, I don't have a clue. Why is it that it's mostly the older hens, the two-year-olds and up, who stop laying when the first-year girls continue right along through the cold months?  Can the younger girls get along with less light, or what?