Those plants look beautiful and healthy.

The condition is probably from 18 hours of light, when they don't need as much the leaves droop down like that then when the lights come back on you should see them back to normal. I usually only keep them on for 12 at the most.

I'd be very curious how much light you give them. One time I gave my plants too much of the plant light and they started growing very small leaves that overlapped each other (my cayenne in particular)...

I would not worry about it. Most times the problems have way of working themselves out if we leave things alone. The fastest way to screw things up, is stop doing what is working so far. As long as they are looking as healthy as they are keep doing what is working for you.

They do not perk back up under the lights. Actually the leaves are curling under and the edges starting to curl in a bit. All my other plants have flat horizontal leaf posture. They look good. Thanks for your responses.