My favorite pharmacological principle

There's this principle doctors follow in prescribing medications: use treatments in the lowest effective dose for the shortest possible time necessary.

The same principle ought to apply in studying. Replace "use treatments" with "study" and you'll get what I mean. After all, who wants to deprive himself by studying for prolonged periods with no appreciable gain in knowledge?

But that's an ideal situation, one that excludes sleepiness and difficulty or incomprehensibility of the subject—and the internet.

These days, though, the battle is against sleepiness. And so I'm thankful for the can of Nescafe that can keep me alive and kicking for at least five hours. I'm afraid med school is gradually turning me into a rabid coffee drinker.

Any alternatives in mind? Coffee makes my heart jump off my chest.