For centuries coffee has filled cups and mugs around the globe, keeping people under the constant influence of caffeine. According to Duke researcher James Lane, PhD, this much-used but littleconsidered drug has a significant effect on our bodies. And, depending on our sensitivity and other health factors, some of us might be better off without it.

Lane has published a variety of studies about caffeine and its effects on the body. He shared a cup of joe with HealthLine and took us on a tour of the harms and health myths that surround caffeine. Rethink what you know bout caffeine and its effects on:

Stress. Caffeine is more of a potentiator than a stimulator, says Lane. “Unlike many other drugs, caffeine doesn’t directly boost nervous activity -- it disrupts a natural process that keeps nervous energy under control.” Caffeine reaches very cell in your body, and in those cells it blocks the effects of adenosine, a chemical that regulates bodily functions. When we become stressed, adenosine levels rise and help to limit the body’s response to that stress. “So if we’re under stress, caffeine exaggerates the body’s response to stress by blocking a natural inhibitor of nervous activity,” says Lane. “Research has shown that caffeine can often make anxiety disorders worse.”

Blood pressure. Lane has shown that when people have caffeine at breakfast and lunch, it elevates their blood pressure and keeps it elevated until 10 p.m. “Even if we’re not still feeling that boost or kick,” he says, “caffeine is still present and still affecting how our bodies function.” When consumed on a daily basis, then, caffeine could be giving your blood pressure a daily boost.

Type 2 diabetes. Lane is skeptical about recent reports that people who are coffee drinkers have a lower incidence of type 2 diabetes. He notes that those reports come from statistical analysis of trends in large groups, not studies that establish direct physiologic effects. “We’re finding that caffeine actually exaggerates the glucose response to a meal,” he says. Once again, stress is the culprit: Caffeine seems to amplify the effects of stress hormones adrenaline and cortisol, which have been shown to exaggerate the body’s glucose response to food.

The bottom line: Lane does not believe that everyone should stop drinking coffee. “We all make choices about the risks we accept in life, whether we ride motorcycles, eat too much ice cream, or live a high-stress lifestyle,” Lane says. “People can decide whether the possible risks of caffeine outweigh the benefits. For all drugs, there are great variations in how each person tolerates caffeine. But if people do have stress-related health problems and they are coffee drinkers, not drinking coffee is a simple thing they can try to better their health. It doesn’t cost anything, and after about a week of withdrawal, it doesn’t have any side effects. In fact, you’ll probably feel better without it.”

Caffstats: Fast Facts About Caffeine

10 to 15 minutes: time it takes caffeine to appear in your bloodstream
60 to 90 minutes: time it takes to reach peak caffeine levels after you drink coffee
3 to 5 hours: time it takes your body to reduce caffeine levels by half
10 to 12 hours: time it takes to clear caffeine out of your system

This means that, if you’re a regular morning coffee drinker, each day you wake up in the middle of caffeine withdrawal. If you drink coffee throughout the day, your body is essentially always under the physiologic effects of caffeine, whether you feel the buzz or not.