Lately I've been trying to sleep at moderately normal hours. Normally I'm awake until at least 6-7am, not so much because I want to be as because I can't sleep before that. So I was going to bed around 4-5am most nights for a couple of weeks. And my head has just been all over the place, nowhere near my normal (at least somewhat balanced) state.
The last about two days I've been a lot clearer mentally, and suddenly it's physically impossible for me to sleep before 6am again.
Guess this is my natural state.

Insomniacs of the world, I'm back. Join me sometime.