Wow. This comment makes me palpitate with joy. Because there is no better compliment than to have a reader so hooked that she can't tear herself away. And because I've done exactly the same thing myself - stayed up until the wee hours totally immersed, even knowing I'd suffer the next day (I hope it wasn't too painful at work) because the story wouldn't let me go. As a writer yourself, you know how special it is for a reader to surrender to your words - it's wonderful to know that you can give the same pleasure to someone else that you've experienced yourself.
Also, I love your abbreviated praise - you're more articulate than I would have been at five in the morning!
In short, this comment made me glow for days. *basks*