Take or leave this as you see fit, and certainly it is not meant and should not be construed as medical advice. Simply that in the spirit of this thread's meanderings: if you're drinking that every day - and you're almost certainly drinking it at least semi-regularly in order to not to feel actively ill from that much caffeine in a single bolus - your daily intake is uncomfortably high. Depending on the exact coffee, 6 espressos is likely close to 500mg of caffeine. Taken regularly, that's enough to increase your baseline level of agitation/anxiety and make you more prone to panic attacks, as well as put you at risk of a number of other, much rarer. issues. Also, at that regular level, caffeine's unlikely to be helping somone perform. Instead it's more likely simply counter-acting the negative impacts of its absence due to the tolerance built up to it. In fact, if the average person took 500mg caffeine in one go, their performance would actually deteriorate (caffeine's effect is U-shaped and 500mg is way to the right of the curve; you're an economist, right? Think of it a caffeine Laffer curve...). 200mg is probably closer to the sweet-spot for the average person, if used to boost performance occasionally.