It is not normal, and it could be caused by a number of factors. How often do you water the plants? How often do you fertilize? Have you ever had your soil tested?

Thanks, opqdan. I try to water just enough to keep it from wilting, fertilize every 3 months or so w/ slow release, and use new, sterile, good quality potting mix w/ added perlite to increase drainage. All the peppers are in pots.

After about 3-4 inches of rain, which laid over several of my cayennes, I had to stand them back up, they started wilting and dropped ALL of the leaves. One was loaded with peppers, the other had only one or two. But they seem to be recovering now. The pole snaps did the same thing!

sounds like a plant with wet feet to me. especially if it starts with the oldest leaves and works towards the younger leaves. they could also be potbound.