Plants Wilting at end of light cylce

Hi, Is it normal for plants to wilt at end of light cycle ? my plants are doing it same time every day, they didn`t do it in veg only when i switched to flower, could it because i have moved light closer ? the 600whps is 20inch above canopy with oscilating fan blowing across canopy, doesn`t seem to be hot, got a temp gauge at canopy level it is 78deg, baffling me? plants are 21" 19" and 16", actually 16" plant wilts more at end of cycle, more drop on leaves, all same strain and when lights come on their all perky, wondered if it is temp as their getting warmer as being in light all day, normally start wilkting 2 hours beofre lights go out. Be greatful for help, also growing in soil

Completely normal

cheers mate, mind at rest now, first grow and got stressed, takes a while to get experienced at all this doesn`t it, be so glad just to get to harvest!!! lol

They're just going to sleep, I wouln't worry abt it, as long as they perk up at lights on, that's normal.