Useful responses one and all. Some responses in no particular order...
I've considered relaxation and/or meditation before. The misses thinks I could do with it, and certainly my finger nails would thank me! Perhaps I should pursue the idea. Oddly, it would suit me. I am naturally (i.e. when calmed down) a chilled and easy going person, and I do believe in all that 'touchy feely' crap!
I do also believe we all have different sensitivities. The coffee's strength is obviously a factor. At a guess, I'd say my 5 small cups equates to maybe 4 espressos as maybe made by your favourite barista. Not shed loads but a fair amount per day. I don't drink any soft drinks (caffeinated or otherwise) at all, and my increased coffee intake is at the cost of green tea. I used to (couple of months back) drink only coffee or green tea (water and some milk excluded). Green tea also contains caffeine, albeit it not on quite the same quantities.
I'm back on the green tea now (day 2), perhaps the caffeine intake there will diminish any withdrawal symptoms from coffee. The big test will come at 11 - that's when the misses puts the coffee pot on. She needs her fix!