Can a plant her from light stress in veg?

I dont have central air and because i only have a swamp cooler i have to crack the door to my veg room sometimes to keep temps down. Will this cause the plants to herm when i switch to 12/12?

Worse - a bad light leak will keep the plant from flowering at all.

I agree . What u can do is cut a vent in your door and use an air filter to light proof it. Unless u dont might ducting running through your house u could cut a duct flange into your door and run 4 ft or so to keep light from reflecting through it .

I've never had a hermie, and I've read a number of times that they are much more rare than most people think, and several things I've read have suspected that sometimes it is inexperienced growers not sexing properly to start with. I dunno how much truth there is to this. Every new grower I run into in real life is obsessed with sexing, jumps the gun, and think growing shoots or other unrelated things are signs of sex (been invited over to a few local closet grows just to confirm someone's sexing, and I find that usually they have no pre-flowers to tell). Who knows how much truth there is to this though... There certainly is a prevailing opinion that light leaks can cause hermies, and when you look at the situation the plant is in out in nature, it does make some sense. I'm super careful about light leaks, so don't have a lot of experience with their effects myself. Hope that at least partially helps