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Coffee and Your Brain, High school

Video looking down at hot coffee being poured into a mug on a table

Many adults drink coffee in the morning to wake up. Coffee has a chemical in it called caffeine.

Does the caffeine in coffee give your body energy?

Coffee doesn’t give you energy

Coffee makes people feel awake, yet the caffeine in coffee gives the body no energy. While you are awake, a molecule called adenosine builds up in your brain and tells you that you are tired. Caffeine sits in adenosine’s spots on brain cells and blocks that tired message for a while.

A 3D ball-and-stick model of the adenosine molecule
Your adenoids, at the top of your throat, carry the same aden- root.

Your word of the day is

uh-DEN-uh-seen

aden-glandfrom Greek adḗn
-os-a kind of sugarfrom German Ribose
-inean ending for chemical namesfrom Latin -ina

A molecule found in all living cells. In the brain, adenosine builds up while you’re awake and helps signal that you’re tired.

A young woman yawning while she works on a laptop at a home desk

An antagonist binds a receptor and blocks the receptor’s signal without turning the receptor on.

Caffeine gives brain cells no energy. Why does blocking adenosine receptors still make a person feel more alert?

Microscope image of brain cells (neurons) from a mouse

Caffeine blocks two kinds of adenosine receptors, A1 and A2A, about equally. In one set of experiments, caffeine still kept mice awake when the mice had no working A1 receptors. Caffeine did not disrupt sleep in mice with no working A2A receptors.

Which receptor do the mouse experiments point to for caffeine’s wake-up effect?

A tired woman resting her head on a café table, holding a takeaway coffee cup

Caffeine is absorbed in the small intestine and carried by the blood.

Which body systems carry caffeine from the mouth to the brain and the heart?

A digital blood pressure monitor and arm cuff on a white cloth, seen from above

In a 1978 study, 250 mg of caffeine raised adrenaline in the blood by 207% and raised blood pressure within an hour.

Which body systems respond when caffeine raises adrenaline and blood pressure?

A white rat against a black background

In rats and mice, daily caffeine increased the number of adenosine receptors in the brain.

How could extra adenosine receptors change what a daily coffee drinker feels when caffeine wears off?

A tabby cat sleeping on the grass

Claim, evidence, reasoning

In rats and cats, adenosine outside brain cells rose during waking and fell during sleep.

Which claim about adenosine and the balance of sleep and waking has the best support?

A gray rat eating a snack beside white rats

Claim, evidence, reasoning

Which evidence backs the claim that adenosine works as a negative feedback signal?

Microscope image of brain cells (neurons) from a study of how neurons use energy as they signal each other

Claim, evidence, reasoning

Which reasoning connects the adenosine measurements to negative feedback?

Espresso brewing from a coffee machine into a small glass

In a 2013 study, adults took 400 mg of caffeine 6 hours before bed. Use a 5-hour half-life.

About how much of the 400 mg dose was still in the body at bedtime?

Microscope image of a cell with its mitochondria glowing blue

Cellular respiration breaks down food and oxygen and forms ATP, and brain cells make adenosine when brain cells use up ATP.

Why can’t caffeine give cells energy the way food does?

A steaming cup of coffee on a table indoors

In the video, Raven says coffee is not giving you energy.

What does caffeine do in the brain instead of giving energy?

Black-and-white photo of a tired man sitting in a kitchen, holding a coffee mug

Why does the tired feeling come back after caffeine clears?

Electron microscope image of cells from normal human blood, including red blood cells

Lesson complete

Today’s word

adenosine

uh-DEN-uh-seen

A molecule made of adenine joined to the sugar ribose. In the brain, adenosine builds up during waking and signals the need for sleep.

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Sources
  1. Christopher Drake, Timothy Roehrs, John Shambroom and Thomas Roth, Henry Ford Hospital Sleep Disorders & Research Center in Detroit, Journal of Clinical Sleep Medicine, 2013
  2. Review by Carolin Reichert (University Psychiatric Clinics Basel), Tom Deboer (Leiden University Medical Center) and Hans-Peter Landolt (University of Zürich), Journal of Sleep Research, 2022
  3. Review by Jennifer Temple (University at Buffalo) with colleagues at Aix Marseille University and Wayne State University, Frontiers in Psychiatry, 2017
  4. D. Robertson, J. A. Oates and colleagues, New England Journal of Medicine, 1978
  5. J. P. DiMarco and the Adenosine for PSVT Study Group, led from the University of Virginia, Annals of Internal Medicine, 1990
  6. J. A. Nathanson, Science, 1984
  7. ChEBI records in PubChem, Caffeine and adenosine
  8. Vision and Change core concepts and competencies, as summarized in Brownell and others, CBE Life Sciences Education, 2014
  9. Emergency use of adenosine, Gebril and Hawes, Emergency Medicine Journal, 2012
  10. Word origins from Dictionary.com: adenosine, adenine, adeno-, ribose, arabinose, gum arabic, -ine, caffeine, coffee, adenoid, receptor, antagonist, antagonize
  11. Spanish and French spellings from Wiktionary
  12. Instagram original of the video, not linked because Instagram needs a login
  13. Transcript from the posted video on YouTube