Same here as with most people, I used to play for very long hours. As a kid, for some reason, I played like that was the last time I'd ever be able to touch a video game ever. Eventually I got over that -- I feel being an adult not only got me enough responsibilities that carving out 4 hours of my time is hard as it stands, but also the feeling that the games are there and will continue to be there for me whenever I want. Recently, I only get the need to play for more hours if I want to be in the zeitgeist for a specific game -- like Monster Hunter, to give a close example.
I also don't think I'll ever pull an all-nighter ever again. Even if I could do it, the idea sounds so quaint nowadays. What is even the point of staying up all night? If I have that much time, why not just sleep like normal and then play the following day?