Those are some awesome looking roots!
Ok, you are correct. I have to, kind of, almost, sort of, take back what I said about my plants not drooping at night.
After carefully comparing several sets of pics, they do droop - a little bit. Nothing like as much as in those shots above. I would call it more like relaxing some. They dont hang down at all, they just dont reach up and prey as much at night.
Its possible my situation is a little different from @Viva_Mexico because my plants mostly have much shorter stems and are shorter plants over all. Long stems will droop more I would think.
I still wonder if at least some of that droop is due to not watering at night.
As faras lack of nutes, that was one way I could tell it was time to feed when I was in soil - the leaves would definitely droop, and the stems got much more flexible/soft if they were thirsty. Much more than with lights out.