If you get up to use the restroom during the middle of the night, still close the door.
My poor wife walked in on me in the middle of the night while I was using the restroom. Now in her defense in the middle of the night I normally leave the lights off so I don't have to stumble around blind and I leave the bedroom and bathroom doors open because our dog does not like it if one of us leaves the bedroom without her being able to follow. I was trying to keep the dog from waking her up.
Well she woke up anyway, and it is bad enough to walk in on someone when you are alert, but when you are dazed and sleepy...its a nightmare.