Hey all, first time bp owner here!

[Homebody]

does it stress your snakes out if you turn a light on at say 9pm to grab something out of their room or put something in, and maybe hangout and watch while they’re actually out of their hides for a few minutes?

Yes, it stresses your snake. How much? That will depend on your how bright your light is, what you're doing in it's enclosure, and most importantly, your snake's personality.