Caffeine: The Biohacker’s Guide

Caffeine is the most widely used stimulant in the world, enhancing alertness, cognition, memory, mood, and athletic performance.

Caffeine is a central nervous system stimulant, enhancing alertness, cognition, memory, mood, and athletic performance.

Biohacker Summary

Too much caffeine will cause anxiety, confusion, headaches, irritation, and rapid heartbeat.

Caffeine (1,3,7-trimethylxanthine) is the world’s most popular – and socially acceptable – stimulant due to its ability to improve reaction time, memory, mood, and wakefulness. It is the most popular nootropic on Earth.

The International Life Sciences Institute found that 85% of the US population consumes at least one caffeinated beverage per day, almost entirely from coffee, soft drinks, and tea. 

Coffee typically contains 2-4x more caffeine than most other beverages, including Red Bull. In addition to coffee, dark chocolate, soft drinks, tea, energy drinks or shots, and pre-formulated nootropic supplements contain caffeine.

The ultimate caffeine and coffee hack we tested is Bulletproof Coffee.

Caffeine consumption produces a boost in mental alertness and athletic performance by reducing physical and mental fatigue.

Studies show that caffeine consumption improves weight loss and glucose tolerance, while lowering the risk of Type II diabetes, Parkinson’s Disease, and several types of cancer.

In this nootropic review, we focus on caffeine’s cognitive enhancement benefits.

Primary benefits:

  • Neurotransmitters – An adenosine antagonist that influences acetylcholine, epinephrine (adrenaline), serotonin and boosts the use of dopamine. Providing the stimulant effect experienced when consuming.
  • Neuroprotectant – Provides a protective effect by boosting the gene expression of brain-derived neurotrophic factor (BDNF). Studies show chronic consumption may protect against developing neurodegenerative diseases like Alzheimer’s.
  • Mood – Improves mood within an hour of consumption. Because it increases the density of GABA receptors, potentiates dopamine, and causes some serotonin receptors to be more responsive.
Nootropic Score

History and Overview

Caffeine (1,3,7-trimethylxanthine) is the most widely consumed stimulant and psychoactive drug on the planet.

Caffeine is a methylated xanthine which are a group of alkaloids commonly used as mild stimulants. Xanthine is a purine base naturally found in most of your body’s tissues.

Caffeine is chemically related to adenine and guanine which are bases of DNA and RNA.

The most common source of caffeine is the coffee bean from which coffee is extracted. Other natural sources include leaves of the tea plant, cocoa beans, kola nuts, holly leaves, yerba mate leaves, seeds from guarana berries, and guayusa leaves.

The earliest evidence of coffee as a beverage comes from 15th century Sufi monasteries in Yemen. By the 16th century coffee made its way north through the Middle East to Italy and the rest of Europe.

Coffee plants were then exported with early explorers and settlers in the Americas.

Chinese legend tells us tea as a source of caffeine was first used in about 3,000 BCE.

The earliest evidence of caffeine use native to the Americas comes from cocoa bean residue found in a Mayan pot dating from 600 BCE.

Today, coffee and tea are drunk in most countries. But typically, one predominates. For example, coffee is the preferred source in Europe and the Americans. While tea is preferred in the UK and Asia.

Despite the world-wide popularity of caffeine use as a stimulant by everyone from students to the military to seniors – the only organization that currently bans the use of caffeine is the National Collegiate Athletic Association (NCAA).

How does Caffeine work in the brain?

Caffeine boosts brain health in several ways. But two in particular stand out.

  1. Caffeine promotes alertness. Caffeine is an adenosine receptor antagonist. Adenosine functions as an inhibitory neurotransmitter in your brain. During the day, as adenosine levels rise, wakefulness decreases and eventually leads to sleep.

    As an adenosine antagonist, caffeine acts by blocking two of four adenosine receptor subtypes A1 and A2A. Preventing adenosine from coupling with these two receptor subtypes increases wakefulness.

    A 13-night sleep lab study was conducted with 18 ‘normal’ young adult males. Each participant received a cup of warm water, 1-, 2- or 4-cups of regular coffee, a 4-cup equivalent of decaffeinated coffee, or a 4-cup equivalent of caffeine.

Regular coffee produced dose-related changes in standard EEG sleep parameters. And 4-cups of coffee acted the same as the equivalent dose of caffeine.

Caffeine caused REM sleep to shift to the early part of the night and stage 3 and 4 sleep to shift to the later than in a normal sleep cycle.

The researchers concluded that coffee and caffeine may be used in normal people to induce symptoms of insomnia.

  1. Caffeine improves physical endurance. Multiple studies show that trained athletes experience improved performance from low to moderate doses of caffeine.

Some studies found improved trial performance, and maximum cycling power. Likely from a greater reliance on fat metabolism and decreased muscle fatigue.

Caffeine helps athletes train longer and at greater power output. And post-exercise recovery benefits from more glucose being taken up by cells and stored as glycogen.

In fact, caffeine can be so effective in sports that the World Anti-Doping Agency (WADA) banned the use of caffeine in athletes from 1962 – 1972 and again from 1984 – 2003.

Caffeine was removed from the prohibited list of drugs but is still part of WADA’s monitoring program to monitor the possible misuse of it in sport.

Caffeine Drawbacks

Scientists first confirmed that caffeine is addictive in 1994. In the same way, you can become addicted to cigarettes, alcohol, or drugs.

In May 2013 caffeine withdrawal was included as an official mental disorder in the 5th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM).

Caffeine affects your body for about 4 hours after it is consumed. Withdrawal symptoms set in 12 – 20 hours after your last dose. The worst symptoms set in after about 2 days and can last for up to a week.

Drowsiness increases

Mood swings increase

↑ Headaches increase

Alertness decreases

Consuming caffeine increases dopamine in your brain which improves mood. Once caffeine leaves your system, you can get grumpy and tired.

Researchers found continuous caffeine consumption increases your number of adenosine, dopamine, and acetylcholine receptors. And is likely why long-term use of caffeine causes tolerance.

Caffeine to the Rescue

Caffeine is the most widely used psychoactive drug in the world. Boosting attention and normalizing mood and cognition.

A study at John Hopkins University showed that caffeine enhances consolidation of long-term memory. This enhanced memory performance occurred 24-hours after caffeine consumption.

This study is especially relevant if you are looking for nootropics for study. Because it means caffeine consumed after a study session helps consolidate memory of what you studied.

Caffeine improves reaction time. And increases alertness and focus.

Coffee and caffeine have been shown to repair DNA damage.

Long-term caffeine use has been associated with reduced risk of diabetes.

Increased caffeine intake is associated with decreased risk of malignant melanoma.

Increased caffeine consumption also protects against cataract blindness.

How does Caffeine feel?

How you feel on caffeine varies from person to person. But for most it depends on how much you consume.

Caffeine acts as a central nervous system stimulant. Once it crosses the blood-brain barrier the most noticeable effect is alertness.

Caffeine stimulates the release of dopamine. Which accounts for the pleasant feeling you associate with your first morning coffee.

Most biohackers find consuming caffeine makes you more productive. You should find it easier to concentrate and get things done.

Using a caffeinated beverage after a study session should help you recall what you studied more easily.

But caffeine later in the afternoon or evening resets your internal body clock (circadian rhythm) and delays the natural rise of melatonin. Your brain’s primary sleep hormone.

So consuming coffee, tea, or an energy drink too late in the day will likely leave you unable to sleep.

And quitting caffeine abruptly can lead to some nasty withdrawal symptoms. See the “Side Effects” section of this review for more.

The Research

Caffeine Reduces Risk of Suicide

Drinking several cups of coffee daily appears to reduce the risk of suicide by about 50% according to a study at the Harvard School of Public Health.

Study authors reviewed data from 3 large studies and found that the risk of adult suicide halved in those who drank 2 – 4 cups of caffeinated coffee per day, compared to those who drank decaffeinated coffee or no coffee.

Caffeine not only stimulates the central nervous system but also acts as a mild antidepressant by boosting the production of serotonin, dopamine and epinephrine.

After analyzing all the data, researchers concluded, “our results suggest an association between greater consumption of coffee and a lowered risk of suicide”.

Caffeine Improves Cognitive Performance

68 U.S. Navy Seal trainees randomly received either 100, 200, or 300 mg of caffeine or placebo in capsule form after 72 hours of sleep deprivation and continuous exposure to other stressors.

Cognitive tests included visual vigilance, reaction time, working memory, and mood.

The chief researcher of the study, Harris Lieberman reported, “Even in the most adverse circumstances, moderate doses of caffeine can improve cognitive function, including vigilance, learning, memory, and mood state.

When cognitive performance is critical and must be maintained during exposure to severe stress, the administration of caffeine provides a significant advantage. A dose of 200 mg appears to be optimal under such conditions.”

Reduces Depression

Recent clinical studies have shown that caffeine intake enhances the effect of antidepressants in rodents.

To find out if it worked in humans, researchers in China recruited 95 male inpatients currently on antidepressant medication. Patients received 60 or 100 mg of caffeine daily or a placebo daily for 4 weeks.

The results showed low dose caffeine improved cognitive performance in depressed patients.

And the researchers concluded caffeine helps reverse the development of depression. And “enhances the outcome of antidepressant treatment in major depressive disorder”.

Boosts Memory

60 undergraduate students at the University of Arizona drank an 8-ounce cup of Starbucks Italian Bold coffee with caffeine or decaffeinated (as the placebo) between 6 – 7 am.

The participants read a book for 30 minutes.

Students who drank the caffeinated coffee performed significantly better than placebo with a 30% improvement in memory.

The researchers performed the same test with 43 students between 2 – 4 in the afternoon. In contrast to the morning session, the students did not experience any memory benefit.

The study authors concluded that “caffeine has a specific benefit for memory during students’ non-optimal time of day – early morning. These findings have real-world implications for students taking morning exams.”

Studies show that older adults also have better memory in the morning. But memory ability declines in the afternoon.

In another study adults over 65 who considered themselves “morning-types” were tested twice over an interval of 5 – 11 days. Once in the morning and once in the late afternoon.

Adults who ingested decaffeinated coffee showed a significant decline in memory performance from morning to afternoon.

In contrast, those who ingested caffeine showed no decline in performance from morning to afternoon.

The conclusion is obvious; older adults perform better in the afternoon when it comes to memory by consuming a caffeinated beverage.


According to the Mayo Clinic, 400 mg per day appears to be safe for most healthy adults. About the amount of caffeine in four cups of regular brewed coffee – or one and a half “tall” coffees from Starbucks.

The American Academy of Pediatrics recommends people age 12 – 18 limit caffeine intake to no more than 100 mg per day.

The half-life is 4 – 6 hours and you experience the effects of caffeine for at least 4 hours.

Be aware that sources of caffeine include coffee, tea, Coke, Pepsi, Dr. Pepper, Mountain Dew, 5-Hour Energy Shot, Monster Energy Drinks.

And one Starbucks tall coffee can contain 235 mg.

So it’s surprisingly easy to quickly exceed your personal limit before you begin to experience caffeine toxicity.

Everyone has a different tolerance level before experiencing the symptoms of an overdose. Listen to your body to know what your personal limit is.

Stacking with L-Theanine

One of the most popular and simple nootropic stacks is caffeine stacked with L-Theanine.

A study with 49 people was conducted at Wageningen University in the Netherlands to assess the effects of caffeine, L-Theanine, and epigallocatechin gallate (EGCG) (which is found in green tea) on mood and cognitive performance.

Study authors noted as little as 40 mg of caffeine has been shown to improve performance on long-duration cognitive tasks, alertness, arousal, and vigor.

The team also noted just 200 mg of L-Theanine improved feelings of calmness, relaxation and less tension.

And when L-Theanine and caffeine were combined there was a significant improvement in alertness and attention-switching task performance. More so than with coffee alone.

The researchers concluded, “these studies provided reliable evidence showing that L-theanine and caffeine have clear beneficial effects on sustained attention, memory, and suppression of distraction.

Moreover, L-theanine was found to lead to relaxation by reducing caffeine-induced arousal”.

The best pre-formulated stack I’ve tried and use is the new Performance Lab® Stim. It contains a natural source (from Coffea Robusta seeds) 50 mg, L-Theanine (Suntheanine®) 100 mg, Ajipure® L-Tyrosine 250 mg, with a balanced NutriGenesis® B-Complex. For alert clean energy without the jitters.

Side Effects

Caffeine is a xanthine alkaloid that can be profoundly toxic and deadly.

But reports of overdoses resulting in death are relatively rare. However, it’s surprisingly easy to go into toxicity territory so please always check the labels on caffeinated beverages and energy drinks.

Doses as little as 200 mg can be toxic to sensitive people.

Symptoms of toxicity include feeling ‘wired’, breathing trouble, confusion, diarrhea, fainting, fever, hallucination, increased thirst and/or urination, heart palpitation, restlessness, sweating, muscle tremors, and rapid heartbeat.

Caffeine is addictive and you can quickly build up a tolerance to its energizing effects. Withdrawal is serious and can include anxiety, fatigue, headaches, irritability, digestive problems, and trouble concentrating.

Caffeine and Modafinil are a powerful combination.

Do NOT combine any source of caffeine with ephedrine, quinolone antibiotics, propranolol, theophylline, certain birth control pills, or echinacea. Check with your doctor or pharmacist if you are using any other medications that may be affected.

Doses of 10 grams of caffeine can be fatal. Although this varies from person to person. In one case a person died from only 240 mg.

A teaspoon of caffeine powder has 3,200 mg.

Available Forms

You get caffeine from a variety of sources including coffee, green or black tea, energy drinks or shots, caffeinated beverages like cola, yerba mate, chocolate, OTC stimulant supplements, some weight-loss drugs, and a few pre-formulated nootropic stacks.

Caffeine is a natural alkaloid found in the seeds and leaves of certain plants. Caffeine in coffee originates primarily from the bean of Coffea arabica, a shrub or small tree that grows in high-altitude subtropical regions of the world.

In comparison, Caffeine anhydrous is manufactured from the beans of coffee plants. “Anhydrous” means without water. Caffeine is extracted from the bean and dehydrated. Which produces a highly concentrated caffeine powder.

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