Coffee definitely affects me and depending on my mood and the amount can give me panic and jittery feelings. Thing is, I have concentration problems and it helps a lot so hard to do without. I think limiting intake to a cup of coffee a day seems to be okay for me, and the biggest thing is how early I drink it. I would say drinking it before the afternoon is probably best. Also making sure I eat, especially a good meal with protein and not all sugar, and don't just run the day on caffeine helps me, too. Half caff is also a good alternative to consider. Or tea.