I had to quit even decaf coffee because it irritates my stomach. I know when I've had caffeine because I get a migraine the day after. I can't take proton pump inhibitors (like Prilosec) because I've taken them for too long already.

I found that cutting caffeine did bring my anxiety down but it didn't help with sleep much. Meditation and "clearing my head" at bedtime helped. However, everybody is different.