If young hens stop laying...
...and each hen starts off with all the eggs she will ever lay already inside her, then does not-laying really mean postponed laying? (he asked hopefully).
We have two two-year-old hens and two one-year-old hens, and none of them have laid an egg for at least the past month. Their coop is pretty small and dark (but cozy), they don't want to go out in the snow, and we've been lucky to get a few hours of sunlight a week for the last two months.
I've read that hens will not lay when they're moulting. The two young ones both started moulting in December. Given the bitter cold temperatures, moulting did not seem a bright idea, timing-wise, but they pulled it off in a magnificent hurry.
The older hens moulted late in the fall. They had all been laying pretty regularly until now, even last winter they didn't slow down much.