When chickens start sitting on their eggs, do they continue to lay them? Or does their biological clock stop until the eggs are hatched? I was wondering because my one hen is sitting on a bunch of eggs and I didn't know if I should be searching for un-sat-on eggs around the house.

Perhaps this will explain,

http://www.msstate.edu/dept/poultry/faq-ans1.htm#rep1

Hens get 'broody', and they do that whether their eggs are fertile (i.e. whether there's a rooster around) or not.

The hoard their own (or other hens')eggs, get testy and tempermental, sit on their nests all day long, and make weird noises when you approach.

Since we have four hens and no rooster, what we do is take the eggs every day, and (as with children) take the hens outside to play in the fresh air. Hens have a short attention span. If you set them outside, they see a grasshopper or whatever, and they're off.

They will return to the nest, however, and you just have to put up with it until their hormones stabilize and they get less 'broody'. They will still continue to lay eggs, but they'll live a more normal life while doing it. Broodiness seems to be an acute phase.

SO- maybe you answered but I just didn't understand?

Does some instinct go off in a hen's mind that says "Stop laying eggs every day. You're sitting on eggs now. You dont need to lay eggs anymore for a while."

Or do they continue to lay eggs in a different spot? Or do they lay them in their clutch of eggs and just know they will not hatch?

This is so confusing!