I have experienced this phenomenon vicariously in a little ascii game called "cataclysm: dark days ahead". It's a very difficult game, but if you get far enough with the genetic mutations you can reach a point where the character's need for sleep is removed. Yes, many other games have day/night cycles and a player that doesn't need to sleep; but the extreme juxtaposition of having needed it for so long and then suddenly not - I cannot think of another game where you can experience that kind of shift. It's really quite jarring at first, but soon feels extraordinarily liberating.