Caffeine Science

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Caffeine Science

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Widely studied in neuroscience, caffeine (chemically known as trimethylxanthine) is the world’s most consumed psychoactive substance, known for its energy-boosting effects on the central nervous system. The caffeine molecule exerts its stimulant effects primarily by blocking adenosine receptors, which normally promote relaxation and sleep. By inhibiting adenosine’s signals, caffeine consumption instead enhances feelings of wakefulness.

Caffeine also increases the secretion of dopamine (a critical neurotransmitter for focus and motivation) and the upregulation of dopamine receptors — as well as making smaller but noticeable increases in norepinephrine and acetylcholine, which support focus and learning. Altogether, the shift in brain chemistry generates the ubiquitous energizing, mood-boosting feeling associated with consuming caffeinated beverages.

Regular consumption of caffeine (given that the timing doesn’t negatively impact sleep) has been shown to have neuroprotective health benefits, and can reduce the probability of conditions like Alzheimer’s and Parkinson’sdisease. This is due to caffeine’s ability to increase the release of catecholamines (dopamine, epinephrine, norepinephrine) and acetylcholine, which are neurotransmitter and neuromodulator systems that are known to be defective in these diseases.

Overview
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Learn about Caffeine Science
Caffeine for Physical Performance
Caffeine for Focus and Cognitive Performance
Guest Experts
Resources
FAQs
Related Topics

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Solo Episode

Using Caffeine to Optimize Mental & Physical Performance

Learn about the physiological benefits of using caffeine for optimal mental and physical performance, from how much you should take to when best to have it.

Learn about Caffeine Science

Caffeine for Physical Performance

Caffeine is considered an ergogenic compound, which refers to its ability to enhance physical performance, particularly in endurance activities. Consuming caffeine at a dosage of about 1-3 milligrams per kilogram of body weight (approximately 100 to 300 mg per day), approximately 30 minutes before exercise can boost performance.

This ergogenic effect affects various aspects of physical fitness, including reaction time and power output. Caffeine before exercise also can make workouts more enjoyable, particularly on days where motivation to exercise is low. However, Dr. Huberman recommends not using caffeine before every workout as it can lead to diminishing benefits for mood and motivation.

The effects of caffeine can vary depending on an individual’s caffeine adaptation and sensitivity. For those unaccustomed to caffeine, consumption before physical activities may lead to negative effects like increased anxiety, elevated heart rate, vasoconstriction and heat retention. This can hinder performance rather than enhance it, especially if not familiar with managing caffeine’s physiological impacts.

Caffeine & Endurance

From Episode

Guest Series | Dr. Andy Galpin: Optimal Nutrition & Supplementation for Fitness

Caffeine, High-Carbohydrate Meals & Timing, Managing Daily Energy

From Episode

Guest Series | Dr. Andy Galpin: How to Build Physical Endurance & Lose Fat

How Pre-Workout Drinks, & Caffeine May Inhibit Performance

From Episode

Dr. Craig Heller: Using Temperature for Performance, Brain & Body Health

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Subtopic: Caffeine for Exercise and Athletic Performance

Caffeine for Focus and Cognitive Performance

Caffeine increases the release of catecholamines like dopamine and epinephrine (adrenaline), which enhances motivation, attention and drive, thereby facilitating improved focus and concentration. Caffeine also acts as an adenosine agonist, reducing the sleepiness we typically feel as the day progresses, thus maintaining a state of wakefulness and cognition.

Caffeine is most effective for memory retention when consumed after a learning session rather than before. This timing allows the increase in epinephrine from consuming caffeine to reinforce memories associated with the learning that just took place. Essentially, caffeine enhances the encoding of new information by taking advantage of the brain’s natural response to adrenaline. Consuming caffeine in appropriate doses, typically 100-200 mg approximately 30 minutes before focused work, can maximize its benefits while minimizing potential side effects.

Tool: Caffeine & Focused Work, Dopamine Efficacy, Alertness

From Episode

Focus Toolkit: Tools to Improve Your Focus & Concentration

Caffeine, Stimulants, Visual Windows & Motivation

From Episode

Dr. Emily Balcetis: Tools for Setting & Achieving Goals

Tools: Caffeine; Timing Peak Learning; “Second Wind”

From Episode

Guest Series | Dr. Matt Walker: Using Sleep to Improve Learning, Creativity & Memory

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Subtopic: Caffeine for Focus and Cognitive Performance

Explore All Subtopics

Guest Experts

Dr. Matthew Walker

Matthew Walker, Ph.D., is a professor of neuroscience and psychology and founder of the Center for Human Sleep Science at the University of California, Berkley, and the author of the book, “Why We Sleep.”

Learn more about Dr. Matthew Walker

Dr. Andy Galpin

Learn more about Dr. Andy Galpin

Resources

Articles & Research Papers

Consumption of caffeinated beverages and serum concentrations of sex steroid hormones in US men (Cancer Causes & Control)
Inverse association between caffeine intake and depressive symptoms in US adults: data from National Health and Nutrition Examination Survey (NHANES) 2005-2006 (Psychiatry Research)
Caffeine stimulation of cortisol secretion across the waking hours in relation to caffeine intake levels (Psychosomatic Medicine)
Time course of tolerance to the performance benefits of caffeine (PLOS ONE)
Blood dopamine level enhanced by caffeine in men after treadmill running (Chinese Journal of Physiology)
The neuroprotective effects of caffeine in neurodegenerative diseases (CNS Neuroscience & Therapeutics)
Expectation for stimulant type modifies caffeine’s effects on mood and cognition among college students (Experimental and Clinical Psychopharmacology)
Caffeine increases striatal dopamine D2/D3 receptor availability in the human brain (Translational Psychiatry)
Caffeinated and non-caffeinated alcohol use and indirect aggression: The impact of self-regulation (Addictive Behaviors)
Caffeine and Its Pharmacological Benefits in the Management of Androgenetic Alopecia: A Review (Skin Pharmacology and Physiology)

The alerting effects of caffeine, bright light and face washing after a short daytime nap (Clinical Neurophysiology)

Frequently Asked Questions

What is the best time to consume caffeine?

In order to maximize the alertness-enhancing effects of caffeine, wait 90-120 minutes after waking before consuming caffeine. As adenosine levels will already be at their lowest immediately after waking, caffeine’s adenosine-blocking properties will have little effect. Delaying caffeine will also allow for cortisol to peak in the morning, and help you become naturally alert. Waiting to consume your first caffeinated beverage of the day can also reduce the need to consume more in the afternoon, which in turn helps improve sleep. Caffeine’s half-life — the time it takes for half of the caffeine in your system to be metabolized — is about 5–6 hours. This is why even if caffeine was consumed hours before bed, it can still negatively impact sleep. Individual differences in liver enzyme metabolism may require stopping caffeine even earlier in the day.For example: If you drink a cup of coffee with 200 mg of caffeine at 3 p.m., about 100 mg could still be in your system by 9 p.m., and around 85 mg by 11 p.m. due to caffeine’s half-life of 6 hours. This lingering caffeine can disrupt your ability to fall asleep or achieve deep sleep, even hours after consumption.

Waiting to consume your first caffeinated beverage of the day can also reduce the need to consume more in the afternoon, which in turn helps improve sleep. Caffeine’s half-life — the time it takes for half of the caffeine in your system to be metabolized — is about 5–6 hours. This is why even if caffeine was consumed hours before bed, it can still negatively impact sleep. Individual differences in liver enzyme metabolism may require stopping caffeine even earlier in the day.

For example: If you drink a cup of coffee with 200 mg of caffeine at 3 p.m., about 100 mg could still be in your system by 9 p.m., and around 85 mg by 11 p.m. due to caffeine’s half-life of 6 hours. This lingering caffeine can disrupt your ability to fall asleep or achieve deep sleep, even hours after consumption.

When should caffeine be avoided?

Certain individuals should consider avoiding caffeine, especially children and teenagers — due to the potential effect of caffeine on brain development. Consuming high doses of caffeine can have cardiovascular effects like increased blood pressure and heart rate, which lead to feelings of anxiety and panic, especially in people prone to anxiety or who are not caffeine-adapted. Its diuretic effects can also lead to excessive urination, so it’s best to avoid caffeine if you are feeling dehydrated or struggle with electrolyte imbalance. People not used to regular caffeine should avoid it before important tasks, such as a test, as it can cause anxiety and disrupt focus. In pharmacology, caffeine can interact with medications, including over-the-counter drugs and compounds like theophylline, leading to amplified stimulant effects. Additionally, individuals with type 2 diabetes should monitor and limit caffeine intake, as it can affect glucose metabolism.

In pharmacology, caffeine can interact with medications, including over-the-counter drugs and compounds like theophylline, leading to amplified stimulant effects. Additionally, individuals with type 2 diabetes should monitor and limit caffeine intake, as it can affect glucose metabolism.

Is caffeine addictive?

Caffeine is considered to be addictive, though it is considered mild compared to other substances like cocaine or opioids. Regular intake, regardless of the amount of caffeine consumed, may result in caffeine withdrawal if caffeine levels abruptly drop. Withdrawal symptoms typically start 12-24 hours after the last dose and include headaches, fatigue, irritability and difficulty concentrating. You can lessen these symptoms by gradually reducing intake over time. Symptoms will usually subside after a few days, though it may take up to a few weeks if your body is used to consistently high doses of caffeine.

How much caffeine is in different caffeinated beverages?

A dose of caffeine is often discussed in comparison to “a cup of coffee,” but caffeine content varies across coffee drinks, and varies even more widely among different types of caffeinated beverages and supplements.A small, 8-ounce (250 milliliter, or mL) cup of coffee contains around 100 mg of caffeine, but can vary depending on the type of coffee beans, vendor and brewing method used — for example robusta coffee beans have almost twice the amount of caffeine as coffee made from arabica beans.Note, decaffeinated coffee is not completely caffeine-free. An 8-ounce cup will usually contain less than 5 mg of caffeine, but could contain up to 15 mg. A single, 1-ounce shot of espresso contains around 70 mg of caffeine.An 8-ounce (250 mL) cup of black tea contains around 45-75 mg of caffeine.An 8-ounce (250 mL) cup of green tea contains around 40-50 mg of caffeine.Soft drinks can vary: A 12-ounce (355 mL) can of soda contains 34-55 mg of caffeine.Energy drinks like Red Bull have around 80 mg of caffeine per 8-ounce can — note, though, that energy drinks also add additional compounds to energy drinks, which can intensify the effects of caffeine.Caffeine pills or powders typically provide 100-200 mg per serving.For further reading: Examine.com offers an excellent resource with additional information on caffeine dosing as well as a thorough answer to the question “How much caffeine is too much?”

A small, 8-ounce (250 milliliter, or mL) cup of coffee contains around 100 mg of caffeine, but can vary depending on the type of coffee beans, vendor and brewing method used — for example robusta coffee beans have almost twice the amount of caffeine as coffee made from arabica beans.
Note, decaffeinated coffee is not completely caffeine-free. An 8-ounce cup will usually contain less than 5 mg of caffeine, but could contain up to 15 mg.
A single, 1-ounce shot of espresso contains around 70 mg of caffeine.
An 8-ounce (250 mL) cup of black tea contains around 45-75 mg of caffeine.
An 8-ounce (250 mL) cup of green tea contains around 40-50 mg of caffeine.
Soft drinks can vary: A 12-ounce (355 mL) can of soda contains 34-55 mg of caffeine.
Energy drinks like Red Bull have around 80 mg of caffeine per 8-ounce can — note, though, that energy drinks also add additional compounds to energy drinks, which can intensify the effects of caffeine.
Caffeine pills or powders typically provide 100-200 mg per serving.

For further reading: Examine.com offers an excellent resource with additional information on caffeine dosing as well as a thorough answer to the question “How much caffeine is too much?”