There are many positive reasons for getting up early (04:30 am), in Bagan. Primary among them is finding a temple (I recommend Pyathagyi Hpaya) to climb which gives you a view of the sunrise, and, for bonus points, a vantage point of the daily tourist balloons which fly over.

Shortly after sunrise you can get to see the tourist balloons taking off, and, for those without the patience to watch them in realtime, here is a taste of what it is like (hint: its much better in real life):