7 Mistakes Coffee Drinkers Make

Mistake: Abstaining on Sweaty Days

What you do: You've heard that coffee seriously dehydrates you, so you skip your fix when the temps are soaring or you've got a tough workout planned.

How it affects you: For a regular java drinker (even just a mug a morning), the withdrawal that comes from giving it up for a day can include not only headaches and lethargy but also muscle pain, apathy and depression, writes Murray Carpenter in Caffeinated, his investigation of modern caffeine culture. And it turns out your suffering is for naught! Lawrence Armstrong at the University of Connecticut published a research review in 2002 that found little compelling evidence that coffee dehydrates us, and a team he led in 2005 found no indication of a diuretic effect when following healthy young caffeinated men over 11 days. Other studies continue to debunk the myth. The reason we are prone to believe it may be because we tend to compare our bathroom habits when drinking coffee—which is, of course, a liquid—with our habits when we aren't drinking anything. (Note: Larger-than-normal or extreme amounts of caffeine may have a diuretic-like effect on the kidneys, but the body will likely adapt over time.)

What to try: Although Carpenter found that the fear of dehydration keeps many athletes from drinking coffee before a race, the jolt can have a significant effect on performance—sometimes increasing it as much as 3 percent. Carpenter puts that in context for recreational exercisers: "A runner who is able to complete a 10K race in 40 minutes without caffeine could shave off 72 seconds with caffeine. And caffeine could allow a cyclist competing in a one-hour time trial to drop a minute and a half."

Mistake: Underestimating the Stuff in the Styrofoam Cup

What you do: You brew some of the discount stuff at home, then get a cup from the gas station on the way into work...and dash out for another a few hours later.

How it affects you: You're probably getting way more caffeine than you realize—or need (hey, how have you been sleeping lately, anyway?). We tend to think that the flavorful brews we get at the sit-down cafe are the most potent, but it's the light-colored stuff at diners and drive-throughs that really packs a punch. Gourmet coffees tend to be made from smooth-tasting arabica beans, explains Carpenter, while less-expensive and store-bought brands are often made from a mix that include robusta beans, which can have twice as much caffeine as arabica. And with any type of bean, some of the caffeine gets burned off in the roasting process, so the darker, more thoroughly roasted brews have lost more of their power than the lighter drinks. "Picture a matrix, with light roast/dark roast on one axis and gourmet coffee/diner coffee on the other," writes Carpenter. "The least caffeinated of the four is the dark gourmet coffee."

What to try: Moderate your caffeine intake by dropping the third cup or ordering a darker French or Italian roast.

Mistake: Not Realizing That Coffee's Power Over Women Waxes and Wanes

What you do: You get the same-size brew every day of the month.

How it affects you: Hormonal fluctuations can slow down caffeine metabolism, explains James D. Lane, PhD, a professor of medical psychology at Duke University Medical Center in Durham, North Carolina, and a longtime caffeine researcher. That's why women who are pregnant (most docs agree that a cup a day is fine during pregnancy) or taking estrogen-containing contraceptives may feel like a little caffeine goes an extra-long way. Lane's studies have also shown that the process is slightly slower during the times of the menstrual cycle when estrogen is highest.

What to try: Switch to a smaller size cup during the late luteal phase of your cycle (or when you usually experience PMS) to see if it makes any difference in how you feel and how you sleep.

Mistake: Using It to Replace Cigarettes

What you do: After finally giving up smoking, your French press becomes your new best friend.

How it affects you: Lane says that smoking is one of the few things that can slightly blunt a caffeine buzz. He explains that the chemical by-products of tobacco kick the liver into high gear, which spurs it to metabolize caffeine faster. Because of that, research has shown smokers have a higher caffeine tolerance and need three to four times more than non-smokers to get the same perk-up effects.

What to try: If you're quitting cigarettes, it's important they realize that the same amount of coffee you usually drink could make you feel agitated, irritable and extra-jittery—not a welcome state at any time, but especially when trying to stick to a tough resolution.

Mistake: Drinking It Too Late...in the Morning

What you do: You follow the medical recommendations to finish your mug before 11 a.m.

How it affects you: New research shows that some people have a gene that causes them to metabolize caffeine quickly, while others can take two or three times as long, says Lane. This means that if you're one of those people who are genetically predisposed to be very sensitive to caffeine, the 8-ounce cup you drink in the morning might not be completely out of your system until after your bedtime.

What to try: There isn't an accessible genetic test to find out which kind of coffee metabolizer you are. But if you're doing everything else the sleep docs tell you to do and you're still finding it hard to nod off, make sure you don't have any caffeine for at least 12 hours before you go to bed. (You can track your caffeine consumption using an app like Caffeine Zone 2 Lite)

Mistake: Trying to Exercise It Out

What you do: You have one refill too many, so you go for a run to get the caffeine out of your system. (Or you try to soak it up with starchy food. Or you drink tons of water in an attempt to, well, flush it out.)

How it affects you: Caffeine molecules circulate through your bloodstream and are eventually broken down by the liver into an inactive form that's then excreted through the kidneys. Experts say there isn't anything you can do to speed up the process once it's already begun.

What to try: Caffeine exaggerates your response to stress, says Lane. This means that regulating your emotions will make you much less likely to have a full-blown caffeine-induced freakout. When you start to feel agitated, Lane suggests going into a quiet room (or putting on noise-blocking headphones) and doing the things that you would typically do to de-stress: meditate, perform a few sun salutations, practice deep breathing.

Mistake: Thinking Espresso Is for Diehards Only

What you do: You shy away from espresso because you think the extra caffeine will make you feel wired.

How it affects you: Espresso packs a concentrated punch of caffeine—but that's why it's served in tiny cups. So a standard shot of espresso actually has significantly less caffeine than an 8-ounce cup of regular Starbucks brew (75 mg vs. 180 mg). Studies show that the sweet spot of caffeine is between 100 mg and around 400 mg—more than that, and you will find yourself climbing the walls.

What to try: An espresso can be a convenient alternative to an easy-to-spill mug for days when you need a fast fix.