Morning coffee = bad; small cups of coffee throughout the day = good, if your goal is maximum stimulus. This study confirms that caffeine does indeed enhance performance, although it does not actually reduce the need to sleep:

The team tested the idea by studying 16 male volunteers who were required to stay awake for more than 28 hours at a time. They were given pills of caffeine or placebos. The results showed that volunteers taking the caffeine pills did better on tests of mental ability and fell asleep less often when they were supposed to be awake, despite feeling sleepier than those on placebos.

I do believe these tests are re-enacted at the end of each semester at colleges across the nation. Except maybe the placebo part...

...unless someone accidentally gets unleaded instead of regular.