I've almost completely switched to decaf coffee (which still has 15-30% the amount of caffeine normally found in regular coffee) after reading "Why Do We Sleep" by Matthew Walker.
And half of the office here is either reading it now or wants to start reading it
The American standard for decaf coffee is to remove 97% of caffeine content[0]. (Note - I couldn't find specific CFRs on an official government site, so it's possible this is just a recommendation and not actually enforced. However, a quick google will confirm that this is the consensus on how things are supposed to operate - I make no comment on how they actually operate.)
And half of the office here is either reading it now or wants to start reading it