Any conservative activist or concerned parent will tell you that video games are dangerously addictive, leading children down a dark path just as destructive as alcohol, drugs or junk food.
That is, of course, ridiculous hyperbole, but there is a nugget of truth in there; some games are ridiculously hard to put down. You spend all day at work watching the clock, just waiting for that moment when you can go home and get back on with the game.
Once you do sit down in front of your TV or PC, time loses all meaning, and before you know it, it's 2am and you need to grab that four hours of sleep before you go back to work and spend your shift waiting to get back to the game.
Maybe it's the gameplay, or the near infinite possibilities, or just the very nature of the game that makes it so easy to lose hours on. Either way, some games just eat up your days, and you're not even mad at them, because they're just that damn good.