Leaves droop when the lights are on..

Hey, guys.. I am growing 4 plants with cfls. Temps never go over 85.. Sunshine mix #4 as soil.. My plants start drooping a couple hours after the lights are on and only get worse until i turn the lights off.. They are on a 18/6 light cycle.. 4 weeks old.. Btw they are nice and green with seemingly no problems.. Why do they droop so severely?

I found that my plants were much droopier with cfl's compared to HID lighting. Depends how droopy ! Pic !

Mouse

Gotta remember that plants are living things, and as such the will move. I've turned on he lights one day and fully half of 20 plants were totally limp. I mean branches laying along the sides like they were dead!!! Totally limp!! They recovered about 2 hrs later. I guess it had something to do with transpiration. They just do shit like that. I did a time lapse video of them a couple years ago, and you wouldn't believe how much they'll move around, especially at night.
You sure they aint doing it when the lights are out too? Could be over watering.

Thanks for the input fellows...