To be honest in Y I think on a night flight having no window can be a bonus. The problem with windows is that if they're not in the exact right position then you struggle to find a comfortable sleeping position. I like window seats because I like to lean against the wall/window and it's annoying when a comfortable position in terms of recline means you're stuck 12in deep into the window, when you want to be leaning against the side of the window ideally. No window is not ideal but it's the gamble of no window vs terrible window. Best outcome is a perfectly aligned window where the rear frame of the window aligns with where your head naturally rests if you lean to that side.