Career Center Blog

May 7, 2013

Is coffee affecting your performance at work?

Is coffee affecting your performance at work?

(Photo: Microsoft Free Clip Art)

At a recent seminar, the presenter -- a friend of mine -- seemed anxious on stage. He kept pacing back and forth and wiped sweat from his brow several times. At the break, I went up to him and asked, "Are you doing OK? Would you like me to get you a glass of water?"

"I'm fine," he replied. "I think I just had a little too much caffeine this morning. I was really tired and wanted to be on my game. Guess the shot of espresso I added to my drip coffee wasn't such a great idea after all."

We Seattleites love our coffee. We're actually 94 percent more likely to prefer espresso to bottled water than the average American. But too much caffeine could negatively affect your work performance.

How much coffee is the right amount?
According to Cristen Harris, PhD, RD, CSSD, assistant professor in the Department of Nutrition & Exercise Science at Bastyr University, "The optimal amount varies for each person and is related to their individual tolerance and sensitivity. Sensitivity to caffeine depends on a variety of individual factors, including how much and how often caffeine is habitually consumed, body weight, physical condition and overall anxiety level."

Average caffeine consumption in the U.S. is 200 mg, or about two cups of coffee, per day. But Harris points out that caffeine levels in coffee can vary based on the roast, brewing method and even the amount of grounds used per cup.

"For example, a lighter roast has a higher caffeine content than a darker roast," says Harris. "To put the caffeine content of coffee in perspective for Seattleites, a 16-ounce [grande] cup of Starbucks' Pike Place Roast coffee has approximately 330 mg of caffeine, compared to about 25 mg in the decaffeinated Pike Place Roast."

Too much can hurt work performance
As my friend found out during his presentation, too much caffeine can have a detrimental effect on performance. "Overconsumption of caffeine can cause anxiety, jitters and nervousness," Harris says. "It can also cause an inability to focus, digestive discomfort, insomnia and irritability."

There are a lot of other sources for caffeine, such as tea, chocolate, soda, energy drinks and even some non-prescription medications -- all of which can increase the amount of caffeine in the body.

... But a smaller amount can be good
While overconsumption of caffeine can have a negative effect on performance, normal consumption can be helpful. "Studies show caffeine improves mood, mental fatigue, reaction time, alertness, visual attention and other computerized attention tasks," says Harris.

I'll drink to those coffee benefits! Or maybe I shouldn't ... I've already had my two cups today.

Lisa Quast is the founder of Career Woman, Inc., a career-coaching and business-consulting company. Email her at

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1 Comment

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Seminar, excessive sweating, anxious?

Maybe caffeine is not the cause.

My guess would be too much alcohol the night before. Sounds more like a typical reaction of
having over indulged.


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Karen Burns Karen Burns is the author of The Amazing Adventures of Working Girl, a career guide based on her 59 jobs over 40 years in 22 cities.

Kristen Fife Kristen Fife is a senior recruiter, career mentor, blogger and resume consultant based in the Seattle area.

Lisa Quast Lisa Quast is a certified career coach, mentor, business consultant, former corporate executive and author based in the Seattle area.

Randy Woods Randy Woods writes about job-search tools, networking techniques and other tips to help you land your dream job.

Former contributors

Matt Youngquist is the president of Career Horizons, a career counseling firm.

Natalie Singer is a Seattle writer, editor and small-business owner.

Michelle Goodman is the author of "My So-Called Freelance Life" and "The Anti 9-to-5 Guide."


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