I'm aware that you're asking how to predict, rather than how to control. Unfortunately the ideas I have on hand are about how to control.

First there's Ferris' hack of taking a cold bath, item 2 of:

http://www.fourhourworkweek.com/blog/2008/01/27/relax-like-a-pro-5-steps-to-hacking-your-sleep/

I have not tried that myself. Second, there's orange glasses:

http://www.cleveland.com/healthfit/index.ssf/2010/06/goggles_with_orange_lenses_blo.html

These seem good-enough and they're cheap:

http://www.amazon.com/gp/product/B0001YXG8S

My own self-experimentation says they seem to help. Wear them when it's dark outside so artificial light doesn't push around your sleep schedule.