So, it depends on the living conditions. My light could only be seen through the door. To see my window one would have to go outside, around the house into the meadow to the back. Not much sense to do that in the dark. And I would have heard the frontdoor. It is a very small house. The front door is directly opposite the stairs leading up to the bedrooms. When my father worked the late shift, I would know when he was getting home. That wasn't so late, still in the timeframe being awake reading was allowed.
Also I could close the window shutters so almost no light was seen outside.