Calculus is a pretty general term; the study of rates of change is a particular calculus. It's certainly the most common one, and so it is properly referred to as The Calculus.
All the numbers I reported are from papers on pubmed and stuff, most of which are linked to from the wikipedia article. I spent several hours reading and re-reading papers; I didn't cite them because my normal blog audience doesn't care. But yeah, you can verify everything by starting out on http://en.wikipedia.org/wiki/Caffeine
Attention fluctuation -- look up biphasic sleep, or studies on the effectiveness of napping.
I'm looking through the sources and can't find a paper on tolerance buildup times nor rebound effects after abstinence. Alas, I only have access to abstracts right now :(
As for polyphasic sleep and napping, it is known that energy levels fluctuate cyclically throughout the day with two peaks, but I'm surprised that you plotted it with a sinusoidal curve that would suggest constant periods and surprisingly, constant amplitudes... of course, without axes the graphs don't say much of anything, but it's still a surprising presentation. You could justify it as being for a general audience, but it has significant risk of creating misconceptions, and weakens this article quite a bit.
By the way, one of the papers finds "Caffeine consumption for 4 weeks also significantly reduced hippocampal neurogenesis compared to controls." Which is not happy news for me.
All the numbers I reported are from papers on pubmed and stuff, most of which are linked to from the wikipedia article. I spent several hours reading and re-reading papers; I didn't cite them because my normal blog audience doesn't care. But yeah, you can verify everything by starting out on http://en.wikipedia.org/wiki/Caffeine
Attention fluctuation -- look up biphasic sleep, or studies on the effectiveness of napping.