Personally, I can't function without coffee no matter what. I've tried to stop drinking it, but when I do, I feel irritable, withdrawn, and I have difficulties functioning in society.

With that being said, I do have to cut down during mania. During mania, I limit myself to one cup a day, however during mixed states, I increase my limit to 2-3 cups and during depressive phases, I will drink as many as 5-6 cups a day because coffee helps offset my low mental energy and focus issues and even helps me feel less depressed when I'm in a depressive state.