Too much coffee?

A simple task today. J, Freya and I would go into town to buy something for someone (can't say what, it's a surprise). We spent hours in Oxford, drank litres of coffee, ate a lot of cake, had a great meal at The Nosebag (despite being served by the 'world's grumpiest person' on the till) and then, when we remembered about the something we hadn't bought, had more coffee and some doughnuts. We're now home and feeling slightly ill. It turns out you can have to much chocolate. Too much coffee? I'm still researching.