Approximately 85 percent of the U.S. population drinks at least one caffeinated beverage per day. Caffeine consumers over age 22 gulp down about 300mg of the stimulant per day, predominantly in the form of coffee and soda.

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.

In other words, habitual caffeine consumption makes the average adult consumer more tired!

So why do tens of millions of Americans swear by their morning brew, or snap awake after can of soda in the afternoon? It seems that the onrush of wakefulness they feel actually arises from the reversal of caffeine withdrawal symptoms, which include headache, sleepiness, anxiety, depression, and an inability to concentrate.

Habitual caffeine consumption is generally recognized as safe, however a growing amount of research is demonstrating that it may be pointless. Instead, it's probably wiser to wean yourself off daily caffeine and strive for a normal sleep schedule -- seven to nine hours a day is great for most adults. Doing so means you may have to endure a week or so of irritating withdrawal symptoms, but afterwards, you'll likely return to a more wakeful state, and with your tolerance reset, you'll also be able to take full advantage of caffeine's stimulating effects at a time when you may truly need them.

(Image: AP)