I'm a new grower, with bout 5 months of growing. I use a tent, but I have a open room veg area next to it. This grow area is in a laundry room. I leave the front tent flap open 24/7. I'm careful about light during the dark period, but I've had several occasions where the dark period was interrupted due to accidents, stuff happens. About a couple of months ago I finally put blackout curtains in strategic spots that helped a lot with light spilling into the flower room. Anyway, in my short experience a little light here and there doesn't effect the plant too much. I've only had one hermie, but I'm not sure if the light was the cause. I really stressed my first plants in various ways. I haven't had issues with hermies, except that one, but have had issues with just about everything else, lol! If you need to work in the dark period, I think you can use a green tinted light bulb, not sure.