Recently whenever we've watched a film I've found myself falling asleep for between 10-30 minutes at some point during the middle.
I usually wake up again and can enjoy the rest of the film without really feeling like I've missed anything. What does this tell you? Does it mean that there are at least 10 redundant minutes in all of the films I've watched? Or is it not really about plot, but something else – maybe I don't feel like I'm missing something, but really I am. In any case, if I'm ever suffering from sleeplessness, I know what I need to do.