Super droop. Just sleeping?

I started these four plants from seed. I was growing them in peat and I think I didn't have enough perlite for aeration and wound up overwatering a few weeks ago. I saved them by repotting into bigger pots, which helped disperse the water I think. But they definitely suffered, especially the lower left one. Stunted and pale.



Earlier this week I saw that one of the plants looked really droopy one night so I stuck my finger in to check for moisture (oh yeah baby) and decided to give them a water. I checked back with them a few hours later and saw all the plants were still drooping and especially the one that first caught my attention. I freaked out thinking that I'd overwatered them again, but then discovered that plants usually droop during the dark cycle. Whew. They always perk up again in the morning. Here's how they look during the night:



The one in the upper right is obviously the super droopy one. Why do you think this is? Do some plants simply droop a lot more than others? Is everything okay with that one or is something else going on?

Also, is it bad to open up the cab during the dark cycle of veg and introduce some room light briefly?

It's fine, and yes, they are sleeping, and that is the reason of the drooping
Your plants are in veg, so light in dark cycle won't stress them too much, but it is bad, and should never happen in flower unless you want hermie seeds and shit bud. Good luck.