Does absolute darkness mean no moonlight whatsoever?

My plants are in their third week of flowering.
My grow room which is one of my bedrooms is absolutely dark and everything. but there is no fresh air. If I open the window during the days, the neighbors will be able to see the lights and during the night if I open the window, there comes a little bit of light from outside from the sky and some scattered street lights. This is not okay am I correct?( having night light in grow room will make the plants reveg right?)
I dont know how to provide fresh air!!
I was thinking why is it that in the grow room we need absolute darkness, and in outdoors there is no problem for plants to be exposed to the sky light, street or house lights and whatnot?

 

isn't it still light?why shouldnt it make the plants reveg?

 

I went and checked it again, there is a lamp post in my alley, some of its light is also coming in.
Dont know If that is different than moonlight.

 

Yes I can put a curtain, I thought the little light that would exist in grow room even after putting the curtain would be problematic.

 

yes very little amount of street light, when you are standing in the room you can see that there is light outside if you look through the curtain and window towards outside, but you couldnt see anything in the room, but it wouldnt be absolutely dark.