I think the person in the window seat controls the window. Those in the middle or on the aisle, can close their eyes or put on eyeshades if they want to sleep. When I'm in the window seat, I tend to keep it open unless the sun is just shining through too brightly.

When I'm in the middle, I have no more right to insist that the person in the window seat put down the shade than I would have to insist that they open it because I'd like to look out. Which sometimes happens - I sit there thinking how much I'd like them to put the shade up, but I'd never dream of asking them to.