If this sort of thing is fascinating to you, and you consume caffeine, you absolutely must spend the short time to learn about antagonistic and reinforcing caffeine usage. I've read a few papers on it, but I'm not finding any of the best ones by googling. This link has a short overview though:

http://arvindn.livejournal.com/57651.html

> What is common to these tasks is that progress happens in spurts, due to the fact that they involve frequent cognitive bottlenecks. A cognitive bottleneck can only be overcome when attention level exceeds a task dependent, typically very high threshold. Clearly, then, antagonistic caffeine consumption results in worse-than-normal productivity, because it flattens the attention level curve and decreases the fraction of time spent at peak attention level. Instead, reinforcing consumption helps maximize productivity (the red line). According to this strategy, the best time to drink coffee is when you are already very alert.

Basically, caffeine gives you a boost, then withdrawal. If you're doing creative work, time your caffeine consumption to your high energy periods, then rest during the withdrawal. If you're doing rote, repetitious work, take caffeine during your low periods to smooth your energy out.

This is incredible for your productivity, especially if you're doing creative work that you can't brute force yourself to finish. Highly recommended, almost should be mandatory for any anyone who consumes caffeine and does creative work.