extended night time wilting

you know how sometimes your plants will droop during the night cycle while they are "sleeping"? well i am vegging a bunch of plants under 18 hrs, in ocean forest and watering with just plain water. 1000 watt mh. before the lights go off, while they are off, and for a few hours after they come back on my plants look VERY wilty, more than ive ever seen for a night time wilt. other than that they pretty much look extremely healthy and great. what could be the problem, any ideas?

Plants don't need to b perky while sleeping they are just no longer absorbing sunlight so the wieght of the leaves bend their stems. 1000 wt mh will produce more than enough large(er) fan leaves. You should b good but post a pic so I can see if it's too much wilting.