I need a translator for the language of women.

I’ve been talking to a girl for a little over a month now. We get along great; our conversations flow easily and are always full of laughter. The only problem is whenever we instant message each other, she always falls asleep! It makes me feel…strange. However, we DO tend to talk for hours..sometimes until two in the morning. Why is it that she falls asleep? Do I give her too much attention?