h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Caffiene is good, especially for getting through days with lots of lectures.
The best source of caffeine is, in my opinion, Red Bull. Stimulation for body and mind if you believe the adverts. I would also advise Vodka (single, double - whatever you choose) and Red Bull. Not especially good if you have work to do, but it gets you nicely drunk,and high at the same time

Lately, I've found that if I drink coffee during the day, it'll really wake me up for a short period of time, and then make me more exsausted then I was before. But this works to my advantage at night when I have large homework assignments, because once I finish my work, I'll conk right out and get a really good nights sleep in only a few short hours.
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What I've found is that if I constantly have something to drink (like Mountain Dew), I will continue to drink it, and have a sustained energy; it doesn't give me a surge, but bumps the energy back up to normal, until I stop drinking it, and the effect wears off within the hour. I don't know if this is the case with all caffeine drinks or just this one, but it works!

Caffeine, however, has a few adverse effects.

Your Body produces, naturally, a chemical that inhibits melatonin. Melatonin makes you sleepy. If you use caffeine, your body is less able to produce melatonin inhibitors, and so you become more and more dependant of caffeine. This is beyond the addictive property, so when you try and quit you have withdrawl and are drowsy a lot.

mojo

The effects of caffeine that i have noticed was that it kept the body up and runninf but had the adverse effect on your mind. There were times where my whole body was really energetic but my mind was slow and sluggish. To counter that i would suggest giving up caffeine and instead try ginseng, that usually works a bit better and doesnt make your head slow.