Is caffeine before an exam a good or bad idea?

by Mark Miller February 18, 2016

Is caffeine before an exam a good or bad idea?

Caffeine keeps you alert, enhances concentration, alleviates fatigue—so it would only be good to drink copious volumes of caffeinated beverages before an exam in school, right?

Wrong, say experts. In fact, too much caffeine can interfere with memory processes. On a history exam, when you’re juiced on java you may be floundering around trying to remember just who won the Battle of Waterloo (it’s complicated, but allied troops under the Duke of Wellington defeated Napoleon Bonaparte’s Grand Armée, if anyone can be said to win in a war).

Take the optimal amount of caffeine

But if you can find the optimal amount of caffeine for your own metabolism, one study found the stimulating chemical can enhance memory. And the amount the study recommends is about half as much as the 400 mg of caffeine per day that healthy adults are advised to limit themselves to.

Excess caffeine can make people feel lightheaded, give them anxiety attacks and headaches and make them feel tremulous.

A Daily Mail article from 2014 says heart palpitations are a symptom of having too much caffeine. However, a more recent study found coffee does not cause extra heartbeats. “Whether or not they have the jitters, most regular coffee drinkers can at least be assured the caffeine probably isn’t giving them extra heartbeats, at least according to an analysis based on a cohort from the prospective Cardiovascular Health Study (CHS),” says an article at

Is caffeine before an exam a good or bad idea? Yes

Nevertheless, the Daily Mail quotes Dr. Brian Morton, chief of the Australian Medical Association Council of General Practice, as saying too much caffeine may case a student’s intellectual performance to suffer along with causing the adverse health effects.

He advises against more than four standard caffeinated drinks a day, split between the morning and afternoon. He says caffeine should be consumed before 4 p.m., presumably so it won’t interfere with sleep. He says more than this amount is dangerous.

Michael Yassa, professor of psychology and neuroscience at Johns Hopkins University, and his team of researchers did a study in 2014 on whether coffee affects learning.

“I have been a coffee drinker for quite some time,” Professor Yassa says in the video at this page. “I’m one of those people that feels like they can’t function without their coffee. And I’ve always been curious about the kind of effect that it can have on my memory and on my cognition.”

The professor gave one group of the students caffeine, and another group placebo. He said before giving them caffeine, the researchers showed them pictures of everyday objects, things like rubber ducks and office chairs.

“Once they got the caffeine they came back 24 hours later and we tested them. We found that those were administered caffeine actually had better retention of the information that we taught them the day before. The caffeine enhanced their ability to say this item was similar but not identical to the one I’ve seen before. Memory consolidation is the process of taking memories and strengthening them and making them more permanent. We found that those who were administered caffeine had better retention of the information that we taught them the day before.

“One suggestion we have in the study is that there is an optimal dose to be able to get this enhancement, and it’s about about 200 mg. Above that dose people start to report some unfortunate side effects, like headaches and nausea and so on, and below that you really don’t get the benefit.”

400 mg per day is the safe limit

Most medical experts say about 400 mg of caffeine per day is safe physically. Dr. Yassa’s findings speak to optimal amounts of caffeine and its effects on memory.

Amounts of caffeine in various drinks and medicines vary widely. Caffeine in 8 ounces of coffee varies from 100 to 270 mg of caffeine, depending on the variety of beans it’s made from and the type of brewing process. Brewed coffee averages about 163 mg in 8 ounces.

Scientific American calls it “popular wisdom” that caffeine enhances alertness and academic performance.

“Popular wisdom holds that caffeine enhances learning, alertness and retention, leading millions to consume coffee or caffeinated drinks before a challenging learning task such as attending a business strategy meeting or a demanding scientific presentation,” the article states. The Scientific American article refers to Dr. Yassa’s study and says the beneficial memory effects come after caffeine ingestion.

Lifelong memory benefits

And caffeine may help not just short-term memory in learning situations, but the ability to remember well late in life.
Scientific American reported on another study, conducted over four years, of 7,000 people who drank more than three cups of coffee per day. The 2007 article states:

“Their findings, published in the new issue of Neurology: Women who drank over three cups of Joe a day were less likely to experience as much memory decline as those who downed a cup or less. And benefits seemed to increase with age: the mega–coffee drinkers were 30 percent less likely to suffer memory loss at age 65 and 70 percent less likely over age 80 than non–coffee drinkers.”

The College Recruiter has an article stating that Nutrition Journal published a 2007 study of 496 college students, of whom 51 percent drank coffee in preparing for tests. Based on that study, some psychopharmacologists concluded the caffeinated students had an advantage.

But that same article advises against taking caffeine right before a test so you don’t get the jitters.

Whatever you do, don’t take so much caffeine or so late in the day that you lose sleep before a test. One problem with excessive caffeine consumption is that you can lose sleep. And sleep loss almost certainly interferes with academic performance.

So is caffeine before an exam a good or bad idea? The bottom line with coffee and test-taking seems to dovetail with advice doctors give about caffeine in general: Too much of a good thing is bad for you.

Mark Miller
Mark Miller

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