Definitions of Circadian Rhythms & Random Thoughts

The circadian rhythm is a name given to the "internal body clock" that regulates the (roughly) 24 hour cycle of biological processes in animals and plants. (The term circadian comes from the Latin circa, meaning "around" and dies, "day", meaning literally, "around a day").
en.wikipedia.org/wiki/Circadian_rhythms

http://en.wikipedia.org/wiki/Circadian_rhythm

Mine are really out of whack right now.  I spent a couple hours outside yesterday and was able to wake up for the first time in several weeks.  I'll try and go outside again today to continue to reset my circadian rhythms.  Modern human life can make these things go nuts.  I've been thinking about eliminating coffee from my diet because I'm trying to get back on a more even plane.  I came across an article http://www.sciencedaily.com/releases/2004/05/040512041022.htm that talked about how caffeine in small, regular doses can help stave off sleep, but does this alter the human circadian rhythm cycle?  I drink caffeine all day, and not always in big quantities... they also state:

As the researchers hypothesized, the behavioral differences between the groups appear to be due to caffeine's effects on the homeostatic rather than circadian system.