I don't know what's happened to me as I get older, but I've noticed I'm waking up earlier and earlier and it's harder and harder to go back to sleep. I fought it and fought it. Then I fought it occasionally, and just got up otherwise. It all sucked. But now I'm starting to realize that life is better if I just get up early.
It would seem my body requires a little less sleep than it used to. I used to really need nine hours at a minimum. But now I'm good with as little as six or seven without major ramifications. What's even better is I don't mind getting up early on vacation. In fact, I prefer it because I go ahead and bike or run before it gets so hot and I've been playing outside and lose ALL motivation to get my exercise in that I want to do.
The next logical step? I might learn how to nap occasionally. It almost happened yesterday, but I predict it will happen at some point during this vacation.