Mmmm, coffee. There's an old joke about my profession (which can be used for any scientific / creative profession really): software developers are simply machines for turning coffee into computer code. Pour in the coffee (fuel) and out comes the code, like magic!
But I always looked at my morning cup of Joe as a sort of guilty pleasure until now. I had no idea coffee had so many health benefits! I try to drink no more than 1-2 small cups per day, and never in the evening as I don't want anything to keep me awake at night. I find it provides a nice boost to my productivity in the morning at work, and sometimes in the afternoon when I'm sleepy from a big lunch.
Most professions have similar sayings:)
I've started following this too in the last few years. It seems to effect me for longer now and this is consistent with most nutritional i.e. don't take any caffeine containing drinks after about 6pm.