I've been noticing my girls have been droopy at night, usually about 3 or so hours before the lights go off. @choosefreedom pointed me to this really good forum topic on plants doing just this. you can check it out here. But to sum it up what someone was saying was there's only so much intense light plants can handle before they get tired or stressed from it, so I am thinking that is a good chance that is what I am seeing. It is also possible I've been seeing a bit of that in the other tent as well. These girls looked perky all day until recently. I'll see how well they perk up in the morning, and if they perk up like they normally have been I'll assume that's likely that case. If they don't, I'll give them some water.