We always had that day, or perhaps full week, when no amount of coffee didn't bring that state of productivity back. No matter how strong, how tasty, it really didn't do much for you, and you started to lose faith in the "All-Mighty-Coffee". The main reason is the very nature of coffee, and the way it works on your body and brain. It seems that, in very high amounts coffee has an adverse impact on productivity. The reason is that at high amounts, caffeine generates tension and anxiety. As you likely guessed, stress and anxiety does not help the creative process. Before drinking your fourth shot of espresso, reconsider if coffee will really help.
An extra coffee can very quickly end up being too much. This is because caffeine encourages the adrenal glands, and consumed in excess, will overstimulate them. Overstimulation will result in an overproduction of adrenaline. This sets your body and mind under pressure, triggering the body's fight-or-flight reaction. Though a little bit of adrenaline surplus can allow you focus and finish your important project, an excessive amount of it can certainly make you anxious, and jittery.
Secondly, is that coffee consumption is addictive. Try to stop coffee cold turkey, and you will see what I mean. Though coffee develops a moderate dependency, there are intense withdrawal issues, involving migraines, somnolence, apathy, irregular bowel movements, muscle ache, flu-like symptoms, depression, anxiety, vomiting, and nausea. On the other hand, if you go through with quitting it, it's a great thing you can do for your body and your connection with coffee. You need to stop drinking coffee for a while, so you can enjoy it more.
For some more detailed information on the issue read our inspiration for this post. is decaf coffee good for you