Here is another post on crinkled leaves I just found. In both posts, we have crinkled leaves. But in the post linked below, the leaves aren't round like mine--they are misshapen and deformed. Not sure how big of a difference that makes:

http://forums.gardenweb.com/discussions/3251706/pepper-leaves-curling?n=1

Ok, I think it's safe to say that this isn't spider mite damage. I'm quite good at spotting adult spider mites and if all my plants were infected with spider mites, I would have seen the adults by now. I don't see them or any webs.

I have the same thing with a couple of my super hots. I think it is related to the temperature and watering mixture, although I am no expert in that regard. I know it has not affected my fruit yet. The bhuts are very plentiful. I also notice it is mostly on the top or outside leaves that it happens to, not the ones that have some shade cover.

It's definitely not spider mite damage, as you would see the little spots all over the leaves from where they mites sucked the chlorophyll out. You don't say what species they are but chinese are known to get crinkly leaves quite badly, usually not a problem to the plant but has been associated with calcium/magnesium deficiencies. You can try adding some cal/mag to their soil.

Hi everyone, I really appreciate the input. At this point I believe this is being caused by severe heat.

1. I agree that it isn't spider mites. The symptoms don't line up.
2. I also don't believe this is insect damage. Why would the insects partially chew up a leaf then pack their bags and leave? Also, the leaves are round and not deformed in shape.
3. I'm confident this isn't underwatering. I water my plants every morning like clockwork and I've never seen any of my plants wilt. However, it is much more likely that this is overwatering. However, I don't see any symptoms of it, such as yellowing of the leaves or dying cells at the tips of leaves--the common symptoms.
4. I don't think this is too much fertilizer. One of my plants had too little nutrients. Adding fertilizer continued with crinkled leaves--only greener.
5. Yesterday it was 101 outside. Here is my most extreme photo. The plant fully bounced back by the next morning without watering.
6. Other than the crinkled leaves, the plants seem very happy--new flowers are on the way.

One more thought. According to this video, the issue can be caused by a calcium deficiency. My fertilizer does have calcium in it, but the calcium will only affect new growth. I haven't given enough time to see if the fertilizer affects the new leaves. This might be due to a calcium deficiency.

https://www.youtube.com/watch?v=nwpYuP1as-M

Over watering and or calcium magnesium defficancy. You could try some smoke masters witches brew. Just mix a little with water and watch the PH.

Leaves trying to grow while simultaneously too wilted. Normal, mine look like that. Don't bat an eye. The leaf is trying to grow while it is so hot/transpiring that it can't get enough water to it, resulting in some crinkles/center bigger than the edges can hold. It is a heat issue and nothing to lay awake at night over.

Alright, so a couple of my plants were due for a little bit of fertilizing. The fertilizer has some calcium in it so I applied fertilizer yesterday. I'm thinking I'll figure this out once and for all. If calcium doesn't change things, then it must be the temperature.

It was 105 yesterday afternoon.