Does an open window in a CLOSED bedroom caused the AC to work harder?

We have 100 degree temperatures every day. We live in a town house and the bedrooms are upstairs. Her bedroom is at one end of the hall, and mine is at the other end. The thermostat is in the hallway. She keeps her bedroom door closed and her window OPEN. I tolerate it because the thermostat is in the hallway and I figure as long as her bedroom door is closed it won't have much of an effect on how hard the AC works. Do you agree?