Caffeine keeps you alert, enhances concentration, alleviates fatigue, among so many other benefits. So it would only be good to drink copious volumes of caffeinated beverages before an exam in school, right?
Maybe, maybe not.
In this article, we’ll find out what to do pre-exams, caffeine-wise.
Why caffeine works before exams
If you can find the optimal amount of caffeine for your own metabolism, one study found that the stimulant can enhance memory.
An article from Scientific American calls it “popular wisdom” that caffeine enhances alertness and academic performance. It says the beneficial memory effects come after caffeine ingestion. 
“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.”
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.
They gave one group of students caffeine and another group a placebo. 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 they’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.
Those were administered caffeine actually had better retention of the information that we taught them the day before.
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.
First of all, excess caffeine can make people feel lightheaded, give them anxiety attacks and headaches and make them feel tremulous.
Second, too much caffeine can interfere with memory processes.
A Daily Mail article from 2014 says heart palpitations are a symptom of having too much caffeine. 
Brian Morton, chief of the Australian Medical Association Council of General Practice, as saying too much caffeine may cause a student’s intellectual performance to suffer along with causing the adverse health effects. 
400 mg per day is the safe limit
Most medical experts say about 400 mg of caffeine per day is safe physically. Prof. 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.
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.”
There's a time for everything, including drinking caffeine
Did you know that there’s an algorithm developed to know how much coffee to drink at exactly when? The Wall Street Journal published an article on the U.S. Army working with the Department of Defense to find out how to get your most alert and high-functioning self. 
While the algorithm was initially developed for the U.S. Army, it could also be useful for ordinary people like us.
According to Dr. Jaques Reifman, the senior research scientist who developed this genius idea throws in this question:
“If you could come to work, drink caffeine and have your mental acuity improved by 40% for four hours, wouldn’t you like that?”
So here’s how the algorithm works –
200 mg of caffeine upon waking up and another 200 mg four hours later for best results.
You can also work backward and time this around your exams.
Keep in mind: drinking too much of a caffeinated beverage may force you to pee in the middle of exams. So just have enough to get the most bang for the cup.
Note as well that it’s best to steer clear of caffeine after 3 PM. This will help you get high-quality sleep and help you avoid waking up in the middle of the night.
Other brain-friendly foods and drinks
Brain foods and superfoods
Blueberries – aside from being a superfood rich in antioxidants – also slows down the aging of your brain and keeps you from neurodegenerative diseases.  You may not notice the effects right away, i.e. pre-exams but it’s been proven for the long haul.
Omega-3 rich foods like walnuts, avocados and salmon enhance cognitive functions like memory and concentration.  As a bonus, they all help lower the risks for chronic diseases like cancer and cardiovascular diseases.
Achieving your optimal cognitive functions like attention, memory, reasoning, and learning languages are already possible with the right nutrition.
Whether you want to learn faster, avoid Alzheimer’s disease, or simply win those memory card games (or mini quizzes like that one), you can boost focus, memory, and mental clarity... all thanks to vitamins.
Like any other tea, green tea can be a good source of caffeine.
The level of caffeine may not be as high as that found in a tall cup of coffee, but it’s enough to get you out of your morning or afternoon slump.
Both coffee and tea give you the caffeine fix that you need, but tea eases into your system and coffee can hit you like a truck if it's a highly caffeinated variety.
Green tea helps slow down the development of Alzheimer’s. According to Medical News Today, “researchers found that the green tea polyphenol epigallocatechin gallate (EGCG) stops the formation of beta-amyloid plaques - a hallmark of Alzheimer’s disease - by interfering with the function of beta-amyloid oligomers. 
Green tea also reduces the risk of Parkinson’s disease. Antioxidants in green tea help prevent brain cell damage, which could cause Parkinson’s disease.  It can delay the onset of Parkinson’s by helping cells regenerate - thanks to the antioxidant EGCG.
Whatever you do, don’t have so much caffeine or take it 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.
So just have 200 mg in the morning and another 200 mg 4 hours later, which you can time around your exams.
For best results, complement your caffeine fix with brain superfoods and good nutrition too.
And if you need a jolt of energy while studying for an exam, here's a golden life hack: coffee naps. Find out why and how by watching this video:
Erectile dysfunction. In combination, those are two of the ugliest words known to man. But can caffeine help you get it up?
Science hasn't found the definitive answer to this question, but one study concluded that fewer men who consume caffeine have problems performing. The study said:
Caffeine intake reduced the odds of prevalent ED, especially an intake equivalent to approximately 2-3 daily cups of coffee (170-375 mg/day). This reduction was also observed among overweight/obese and hypertensive, but not among diabetic men. Yet, these associations are warranted to be investigated in prospective studies