That wouldn't be that unusual a night for me. I just get up whenever my body decides it's time. If I need a nap later, I just take one. I've found the older I get, the more common it is for me to get up on my own quite early; I just don't need as much sleep during the night as I used to. Rather than fight it, I just accept that it's just my sleep pattern.

If it's earlier than that, I might read for a bit and see if that will cause me to get drowsy -- it usually works. Sometimes I'll go into the living room and turn on something really boring on the t.v. like a news station and just lay there for a bit; often that will lull me back to sleep.