I am a sign language interpreter. The effects of coffee are condusive to my work: increase of short term memory, increase of alertness, reduction of fatigue, and effects wear off after a period of time similar to most jobs. Plus delicious.
Likewise, small amounts of alcohol (1 or at most 2 glasses) has been shown to increase creativity. As with coffee you will have to check your own personal reaction to it.
Thus spake Eliezer:
It seems that many here might have outlandish ideas for ways of improving our lives. For instance, a recent post advocated installing really bright lights as a way to boost alertness and productivity. We should not adopt such hacks into our dogma until we're pretty sure they work; however, one way of knowing whether a crazy idea works is to try implementing it, and you may have more ideas than you're planning to implement.
So: please post all such lifehack ideas! Even if you haven't tried them, even if they seem unlikely to work. Post them separately, unless some other way would be more appropriate. If you've tried some idea and it hasn't worked, it would be useful to post that too.