my room has a few light leaks fro the veg room. not a ton but enough that i can KINDA see whats in front of me... kinda. i figure as long as its not more then what the moon can put out during a clear night you should be ok, note... i have played baseball at 2am before in the desert once during a full moon. in my first grow, i even had a led on the ac that was bright enough that i could read in there with them and they still flowered jsut fine.