A while ago I tried eliminating all caffeine (I typically drink a lot of diet Coke and coffee). The first few days were hell, and I pretty much sat staring blankly at my computer. Then I had a couple of really magical days where I felt quite alert even in the typically drowsy afternoons. And what was weird was that I seemed to dream more vividly (and remember my dreams). Then I fell off the wagon... at some point I need to try that experiment again, because I think I was onto something.