In the forces I spent a lot of time on stand-by in a crew room drinking some 10-12 large cups of coffee a day and wondering why I couldn't sleep!!!
I then switched to decaf and had the most wonderful nights sleep. Now I have one to three cups of full-fat coffee a day, the rest is decaf. On the rare days I do have the three - I can tell I've had them!
I do like iced coffee, too, but the UK isn't the most favourable climate for drinking it most of the time!
