they go into a resting state at night.....almost all plants do...
by turning the lights on for a few min will NEVER ever ever ever make them revert back to vegatative cycle from flowering, they needs days of continuous light to start that process which takes 4-12 weeks depending on how far into flowering they are..the further along the longer it takes...
when a plant reverts back to veg it essentially takes all the calyx's it has grown and converts them into fan leaves and new branches.
if they are perking back u during the day then overwatering is not the issue, temp drops will also make them droopy. If they maintain the droopy look after an hour of lights on chances are its not normal, when they see that light they usually perk up pretty fast readying themselvs for a days work
I don't know where to start with that...
As I said, one peek will j
ust lose the growth you were going to get that night. Yes your correct it would take many interruptions to revert it.
Calyx's don't transform into leaves, that's absurd. It simply switches growth mode, any flowers include pre flowers that are already there will stay there.
You are correct there are many variables that can cause drooping. None the less a perfectly balanced; healthy plant just waiting to burst out in growth will reach for the sky 24/7.
Even the heaviest Indica leaves the size of your face can and will reach for the sky. Plants may appear healthy but have many deficiencies just like humans.
Unless your balancing you Boron, Silicon, Calcium, Nitrogen, Phosphorus, Magnesium, Potassium and water perfectly; you will have deficiencies. Most are not obvious and cause things like lower yield, slow growth, less bug and mold resistance. Some more obvious with yellow leaves, weak plants, purple branches.
OP it could be any number of reasons why its droopy. Best thing is to keep a log of every grow and everything you do in it. That way you will soon be able to identify the root cause of any issue you come across and be making suggestions to us!