Java-enhanced student

How much is too much caffeine?

Coffee has a number of actions on the entire body—some more pleasant than others. Four out of five Americans depend on a steaming cup of joe or a well-timed cola to give their central nervous system a boost to chase away morning grogginess, rescue a sleepy afternoon, or ensure a few more hours of productivity.

Caffeine is without a doubt the world's stimulant of choice. Most adults consume about 300 milligrams of caffeine on a given day—that's equivalent to about four cans of Mountain Dew, four cups of tea, two regular strength No Doze, a 10 ounce bar of chocolate, or two eight ounce cups of non-gourmet coffee.

If you like coffee house java however, you may be consuming much, much more. A Starbucks Grande, for example, contains a whopping 550 milligrams of caffeine. Just one cup will put you well over the top of what most health experts believe is a safe amount of caffeine.

What effects does caffeine have?

It is known that caffeine can affect heart rate, temporarily raise blood pressure, stimulate the nervous system, and increase digestive tract activity—it's not your imagination, a morning cup of joe can indeed act like a mild laxative. However current research shows caffeine does not raise the risk of heart disease and for some may lower the risk as well as reduce risk of type 2 diabetes. In addition, coffee has been found to have positive impacts on the liver, reduce risk of some cancers, and early studies suggest it may have positive impacts on some other diseases.

Research documenting a relationship between coffee consumption and bone loss in women brings a whole new meaning to the term "coffee break." Women who drink coffee may be substituting it for the all-important daily glass of milk and subsequently their diet is lacking in calcium.

In fact the diet and lifestyle profile of the heavy coffee drinker is quite different from non-coffee or decaf consumers: decaf drinkers tend to take more vitamins, exercise more regularly, eat more green veggies, and buckle up more often than other coffee drinkers. Heavy coffee drinkers ingest more fatty foods, drink more alcohol, and generally smoke more than their non-coffee drinking cohorts. Coffee compulsives, the ten-cup-a-day people, might be well advised to give themselves a break by cutting back.

What to expect when taking less caffeine

Even at surprisingly low doses of caffeine (250 milligrams), you may be at risk for caffeine withdrawal. Even though you drink only two cups a day, your body can become dependent upon it. Stopping abruptly can result in moderate to severe withdrawal headaches.

You can stave off the headache by reducing your caffeine intake very slowly rather than going cold turkey. Surprisingly, taking two pain relievers may help your caffeine headache, but may not be helping you in your effort to cut back. Look at the ingredient panel and you will notice that caffeine is a central ingredient in many pain relieving products. Aspirin and other painkillers get a pretty substantial power boost from caffeine. Two Exedrin have about as much caffeine as a cup of coffee.

Keep it in moderation

You may want to rethink increasing caffeine to help you through finals. Although caffeine is a powerful and proven stimulant, there are ways that caffeine could harm your performance on your exams.

One researcher suggests that although rare, caffeine may have a paradoxical effect on some people—they may react to it as though it were a sedative. More commonly however, is that very large doses might promote a state of endless withdrawal and tolerance thereby interrupting sleep patterns and causing sedation. In these instances, stopping caffeine intake may help overcome sleepiness. 

Drinking even small amounts of caffeine can interfere with a good night of sleep. While maximum effects are experienced within 30–60 minutes of drinking a caffeinated beverage, it takes much longer for the effects to wear off. It typically takes 4 to 6 hours—that is why sleep is so often disrupted.

A mid-evening soda or coffee is still lingering in the bloodstream when it's finally time to close the books and hit the hay. Stories of students falling asleep or crashing during a final exam are not unusual. Caffeine is often a central culprit. Having ingested large doses to ward off sleep for cramming, the effects, combined with a lack of sleep, eventually catch up, sometimes in the midst of an exam.

Finally, caffeine can either help or hinder your performance depending on what type of task you are tackling. If you have an afternoon of problem sets, or a paper to proofread, a cup of coffee or soda might speed up the process and improve your performance. Caffeine has been shown to speed up the reaction time and the automatic processing skills required for these tasks. If you have to interpret a poem, analyze or critique a research article, or do a series of statistical sets, you may do better by laying off the caffeine. Caffeine worsens performance on more complex tasks.

Rather than relying on caffeine to see you through finals, far more benefit can be derived from proper nutrition, a consistent and well-rounded exercise program to boost your body's natural energy level, and a regular sleeping and studying schedule. If you keep your caffeine intake at approximately 200 milligrams a day, you need not worry about negative health effects and can redirect your focus to your studies instead.

Improve sleep quality

It will probably come as no surprise that improving the quality of your sleep will help you perform better overall, even without caffeine. Student Health & Wellness offers the free Refresh sleep program to help all University of Iowa students boost the quality of their zzzs. 

University of Iowa students can schedule an appointment with a provider at Student Health and Wellness online through their MyChart account or by calling 1-319-335-8394.
Last reviewed: 
August 2017

Interested in using our health content?