Overexposure to caffeine (yes, even chocolate!) can reduce blood flow 25%. Constriction of blood vessels, reducing blood flow, is one mechanism by which caffeine can help migraines, (and that’s a good effect) but is also how it contributes to reduced brain function. With caffeine, your brain will be “hyper” with faster firing neurons, but they won’t produce your best neuronal work …
How much caffeine is too much? The answer can depend on your genes. Yes, you have coffee genes! Actually, caffeine-sensitivity genes determine whether you slowly or quickly metabolize caffeine. Slow caffeine metabolizers are at increased risk for infertility, heart attacks, sleep disturbances, anxiety and miscarriage with caffeine use. Fast metabolizers will actually reduce their risk of heart attack with 2-3 cups of coffee daily. If you have any of these symptoms after 1-2 coffees, sodas, or hot chocolates, you may have caffeine sensitivity: jitteriness, increased heart beat, nausea, sweating, dizziness, diarrhea, insomnia or headache.
Frequently drinking coffee or caffeinated sodas, or eating chocolate actually increases your caffeine tolerance over time, reducing symptoms. That would seem helpful for the caffeine sensitive – but it unfortunately does not reduce the health risks of caffeine sensitivity.
Enjoy, with mindfulness of your uniqueness.