But if you’re a daily drinker of caffeine, relying on your morning espresso for an A.M. jumpstart, or can of Coke for an afternoon pick-me-up, chances are, you’re consuming caffeine all wrong. Though everybody reacts differently to the drug, most habitual users receive little to no benefit from caffeine; it neither enhances mental performance nor mental alertness.
To the novice caffeine drinker, a cup of coffee is an awakening experience. Metabolism is boosted, along with alertness and even physical endurance. These effects are rooted in cerebral subterfuge. Caffeine molecules from the beverage weasel their way to the brain where they sneakily bind to adenosine receptors. These receptors, which produce feelings of tiredness and fatigue when filled with adenosine, a by-product of cellular activity, don’t respond to caffeine. This allows the body’s natural stimulants, dopamine and norepinephrine, to persist at higher levels.
But the body doesn’t remain fooled for long. As few as three weeks of daily caffeine consumption over 100mg (roughly one cup of coffee) prompts the nervous system to increase the number of adenosine receptors. The greater amount of receptors makes you more susceptible to the fatiguing effects of adenosine, and means you need to consume more and more caffeine to fill those receptors, and thus stave off fatigue.