Agreed... but we want to test how much his reaction to his coffee is dependent on the experience of drinking coffee versus it's actual caffeine content, so I'd suggest he takes it reasonably close to how he normally takes it, to get the same trigger. We already know he doesn't react to a caffeinated drink (his tea) that doesn't taste like his usual coffee.

In other words, if he normally takes it black with no sugar, lots of cream and sugar might break the experiment.