Doc, what is up with that? I do the same thing, almost every night, wake up at 3am and can't get back to sleep. I never used to be like that, I always slept through the night.
I was thinking mine might be attributed to pre-menopause, but I know you are a lot younger than me, and even I am pretty young to go through that. So who knows what its about. Insomnia, I guess, yet I'm not really worried about anything in particular.