I'm not an expert but from the books and articles I've read, it's suggested to cut out caffeine completely. I used to drink coffee every day and if I was tired in the morning, I could drink a coffee and feel sharp. Now I'm unable to drink coffee as it gives me headaches and my brain can't handle it.

Once in a while, I do drink a lattee if I'm having a good brain day but I don't drink any other caffeinated products. I know it's hard to just accept feeling lousy but I think in the long run it will pay off more than the quick fix of the feeling you get from caffeine jolt.