You're partly right, actually. Dry heat: taco, moist heat: drooping. Taco'ing is from the leaves drying out and causes them to become crispy (crunchy tacos). Moist heat basically steams the plant like dinner vegetables. There's no drying because of the moisture, and therefore no taco'ing, but the leaves become soft & wilt like steamed cabbage.
Well let's see what's going on. Please post any of the following info that you're able: the light(s) you're using, how far they are from the plants, how you cool the light(s) & manage air circulation for the plants, room temp and the temp under the lights at the plant tops. I'm assuming this end-of-day drooping happens whether you've watered recently or not. Of course, please post anything you notice about when the drooping is better, worse, or days it doesn't happen at all.
I'm using a 600w hps dual spec lamp that is around a foot and a half away due to heat
And that is cooled by a fan hanging beside it and the exhaust fan is below here to suck the heat straight from the bub.
I have two air intake fans with the exhaust so it circulates the whole room in seconds.
The temp is constant throughout as my bedroom keeps it war and that stay around 75-80 fahrenheit.
The droop doesn't happen after water but started two days after, I have perfect drainage and runoff. The droop only happens around the last two hours and now happens everyday ?