Caffeine: A User's Guide to Getting Optimally Wired

Caffeine is the most widely used stimulant in the world, but few use it to maximal advantage. Get optimally wired with these tips.

1) Consume in small, frequent amounts.

Between 20-200mg per hour may be an optimal dose for cognitive function.

Caffeine crosses the blood-brain barrier quickly (owing to its lipid solubility) although it can take up to 45 minutes for full ingestion through the gastro-intestinal tract. Under normal conditions, this remains stable for around 1 hour before gradually clearing in the following 3-4 hours (depending on a variety of factors).

A landmark 2004 study showed that small hourly doses of caffeine (.3mg per kg of body weight [approx 20 mg per hour; thanks digg!]) can support extended wakefulness, potentially by counteracting the homeostatic sleep pressure, which builds slowly across the day and acts preferentially on the prefrontal cortex (an area of the brain thought responsible for executive and "higher" cognitive functions).

At doses of 600mg, caffeine's effects on cognitive performance are often comparable to those of modafinil, a best-of-class nootropic.

2) Play to your cognitive strengths while wired.

Caffeine may increase the speed with which you work, may decrease attentional lapses, and may even benefit recall - but is less likely to benefit more complex cognitive functions, and may even hurt others. Plan accordingly (and preferably prior to consuming caffeine!)

Caffeine has long been known to improve vigilance, but work focusing on its more more cognitive effects - through interactions with the "frontal task network" - show less clear effects.

In tests of lateral prefrontal function, caffeine only remediates some fatigue-related symptoms. For example, in a random number generation task (a commonly-used measure of prefrontal function), caffeine increased the quantity of numbers generated to pre-fatigue levels, but did not significantly affect more demanding aspects of performance: caffeine didn't affect the likelihood of subjects generating numbers outside the acceptable range, or their tendency to perseverate on particular numbers.

Another study indicates the same is true of caffeine's effect on the medial prefrontal cortex. In that study, sleep deprivation-related decrements on the Iowa Gambling Task were not mitigated by caffeine.

The Stroop task, which a wealth of neuroimaging shows is related to functioning of the anterior cingulate, may also benefit from caffeine, but this effect may also be due to general speed improvements rather than those of cognitive control specifically.

(Interestingly, it appears that none of these studies follow guideline #1 - and there are hints in the second one that subject's performance might have shown significant improvements if another dose of caffeine had been provided about half-way through the task).

Recall from memory may be improved by caffeine (here and here), possibly due to enhancements in memory encoding rather than retrieval per se. Another study shows caffeine can actually impair estimates of "memory scanning" speed (in the Sternberg paradigm), so the failure of many studies to find recall-related effects of caffeine may reflect a speed-accuracy tradeoff at the time of retrieval.

3) Play to caffeine's strengths.

Caffeine's effects can be maximized or minimized depending on what else is in your system at the time.

The beneficial effects of caffeine may be most pronounced in conjunction with sugar. For example, one factor analytic study has shown caffeine-glucose cocktails provide benefits to cognition not seen with either alone.

Some flavonoids (such as soy) may act in the same way as caffeine - i.e., through adenosine receptor antagonism - in particular galangin, genistein, and hispidol. Evidence showing that markers of caffeine metabolism are slowed by flavonoids might suggest that ingestion of flavonoids would enhance the effects of caffeine - some studies show grapefruit juice might keep caffeine levels in the bloodstream high for longer, though others have found no such effect (thanks to commenter Matt McIntosh for this latter reference).

Caffeine's effects might be masked by green tea extract, Kava Kava or St. John's Wort - all of which contain theanine and are associated with subjective feelings of relaxation - but other preliminary evidence indicates the opposite effect: theanine might actually potentiate the benefits of caffeine on some tasks (reported in longer format here).

Similarly, nicotine may speed the metabolism of caffeine.

Because caffeine is a competitive antagonist for adenosine 1 & 2a primarily at striatal sites, it may also selectively increase the efficacy of D2 receptors, given evidence that D2 depleted mice show reduced effects of caffeination. According to theoretical computational models of D2 receptor activity in the striatum, this should increase cortico-thalamic excitability. It will be important for future work to examine caffeine's effect on tasks thought to require NoGo pathway activity.

A variety of other chemicals may work on the A2 receptor in similar (SCH 58261, ZM 241385, CSC, KF17837) or opposing ways (CGS 21680, APEC, 2HE-NECA).

4) Know when to stop - and when to start again.

Although you may not grow strongly tolerant to caffeine, you can become dependent on it and suffer withdrawal symptoms. Balance these concerns with the cognitive and health benefits associated with caffeine consumption - and appropriately timed resumption.

Long-term ingestion of large quantities of caffeine (by way of coffee) is associated with a variety of health benefits - not only cognitive enhancements but also reduction in risk for type 2 diabetes (c.f.), Alzheimer's and Parkinson's . These beneficial effects may be related to the neuroprotective role of adenosine.

However, there are some suggestions that caffeine also has adverse effects (mostly cardiovascular, which might be balanced by flavonoids - see guideline #3). And some people just don't like the thought of cultivating an addiction - or the spectre of withdrawal symptoms.

Some evidence indicates high heritability for caffeine addition (note: this is based on interviews of twins) and others are advocating the recognition of caffeine addiction as a bona fide mental disorder. Withdrawal symptoms can onset within 12 to 24 hours of caffeine consumption and last between 2 and 9 days.

There are more cognitive concerns here as well. For one, caffeine probably follows the Yerkes-Dodson law, in which a moderate dose is superior to too little or too much. In addition, there are well-established cognitive effects where recall is best when it matches the context of encoding - so if you're caffeinated when you study for the test, you better be caffeinated when you take it.

5) Finding good sources of caffeine

Despite the huge variety of sources of caffeine - including caffeinated soap, candy, and of course chocolate - the optimal use of caffeine is likely to involve small, hourly doses along with some cardioprotective agent. Given the high solubility of caffeine, absorption time should not be an issue (but if for some reason it is, try gum).

Otherwise, why not enjoy a cup of green tea (coffee-flavored, if you must), as the Chinese have for nearly 5000 years? It's hard to come by a better longitudinal study than that.


More like this

There are 13 new articles in PLoS ONE today. As always, you should rate the articles, post notes and comments and send trackbacks when you blog about the papers. You can now also easily place articles on various social services (CiteULike, Connotea, Stumbleupon, Facebook and Digg) with just one…
In a small study of female college students, researchers found that a caffeine supplement seemed to lessen the muscle pain that crops up a day after a challenging workout. Just when we got our membership card into the haughty I-Eshew-Coffee club, they publish this little study. We confess we're…
In his epic poem Visions of the Daughters of Albion, William Blake asks: "Where goest thou O thought? To what remote land is thy flight?" More than two centuries later, memory remains as one of the enduring mysteries of neuroscience, and despite decades of intensive research using modern techniques…
"Working memory" refers to the cognitive processes involved in temporarily storing & manipulating information. Unsurprisingly, this capacity is correlated with many measures of intelligence, but (somewhat more surprisingly) is also impaired in a variety of neurological disorders, including…

Nice, it give me a tip especially for my health. I appreciate you for giving such a useful blog. this website was not only knowledgeable but also very artistic too.

Have you ever considered adding more videos to your blog posts to keep the readers more entertained? I mean I just read through the entire article of yours and it was quite good but since I'm more of a visual learner,I found that to be more helpful. Just my my idea, Good luck


Check out my blog at How to lose weight fast

I like your blog and it was so good and I am gona bookmark it. I Have to speak the excellent analysis this article has is greatly incredible. No one goes that extra mile these days? Well Done!!! Just one more tip you can install a Translator for your Worldwide Readers.

Since I am caffeine sensitive, reading this post was both really interesting and informative. I love coffee so being sensitive to caffeine is really annoying, but maybe now I can enjoy drinking it without having to feel sick all the time. Thank you for sharing this.

As a foodie I prefer to eat over pretty much anything else. But I love to workout, not only because it keeps me in shape but because I can eat more! It also helps me gain weight which is my main focus. I eat very healthy and I find it hard to gain weight unless I overeat which is never fun!

Oh my goodness! an amazing article dude. Thank you However I am experiencing issue with ur rss . Donât know why Unable to subscribe to it. Is there anyone getting identical rss problem? Anyone who knows kindly respond. Thnkx

Can I just say what a relief to find someone who actually knows what theyre talking about on the internet. You definitely know how to bring an issue to light and make it important. More people need to read this and understand this side of the story. I cant believe youre not more popular because you definitely have the gift.


What kind of an effective does it has on patients with high risk of hypertension? I know it doesn't go well but are even smaller quantities risky? What if a small dose is taken after a brick walk or a light exercise schedule?

Although I like the information discussed in this article about caffeine, I am still pretty skeptical about the good effects of caffeine. For instance, when I am eating chocolate, I don't see that of a difference. Also, when drinking Coke or consuming other beverages. Maybe in more natural sources caffeine is effective, but I don't see a major difference.

Ray Wilson

You say that Kava Kava and St. John's Wort contain theanine - is this true? Wikipedia says theanine is found in tea and the basidiomycete mushroom, but I've never heard of these other herbs containing it. Kava, St. John's Wort, and theanine are all used for relaxation, but I thought they had different active constituents and mechanisms of action.

Very nice article. My own maximum caffeini intake is about 400mg, if get more caffeine than that it usually affects my sleep.

caffeine artificially forces the body into fight or flight mode. it directly raises cortisol levels in the body. when the body is in a constant state of stress, it must constantly release adrenocorticol hormones. over time, this leads to a compromise in the body's ability to produce DHEA, the precursor to both testosterone and estrogen. cortisol is an anti-inflammatory hormone, when the body can no longer make it in sufficient quantities there is widespread inflammation, particularly of the digestive tract. this leads to malabsorption of nutrients. over time this can promote a state of bacterial disbiosis, which may lead to coeliac disease, ulcerative colitis, irritable bowel, etc.

with DHEA low in the body, there is less production of sex hormones, which leads to depression, lack of sex drive, lack of vitality, malaise, etc.

take both together and after enough time you feel depressed, no sex drive, and constant digestive upset.

as caffeine puts the body into fight or flight response, it shifts mental activity away from the prefrontal cortex (seat of abstract reasoning) towards the limbic system (seat of emotional reactivity). you may be more aware and hyperfunctioning, but your cognitive processes aren't anywhere near as high as they should be.

caffeine stresses the liver and over time causes a state of congestion. liver congestion impairs metabolism and synthesis of proteins, and leads to a state of fatigue, depression, and irritability, and increases the likelihood of fatty liver and damage caused by hepatitis.

so, in short, given enough time and a high enough dose, caffeine will make you tired, depressed, gassy, and bloated. it will decrease testosterone and diminish your sex drive. It will cause serious digestive complaints. it will make you high strung and stupid, even while you think you are hyper-aware.

how is this supposed to increase your intelligence?

this post sounds like it was written by an addict trying to justify behavior.

you're also overly stressing the intelligence of the mind, while completely dismissing the intelligence inherent within the mind-body connection.

lastly, the studies seem rather hand-picked. you can find more than enough to prove the opposite is true. I was hoping mentat-wiki (with a name like that) would have more intellectual integrity. let's try and raise the bar. next time, try a little harder and write some cons in addition to a list of biased pros.

Nice post.You share valuable information and excellent design you got here!
I would like to thank you for sharing your thoughts.

Nice post.You share valuable information and excellent design you got here!
I would like to thank you for sharing your thoughts.

Do you wish to attending like Brad Pitt? Go for polarized sunglasses shop online. This beauteous ellipsoidal brownish anatomy has spiral arise rim. The two accessible shades of Brown Dark Havana and Ruthenium Smoke accomplish the attending added appealing. The adventurous comatose hooks in atramentous add a birr of arrogance.

200mg an hour is too much. You shouldn't exceed 600mg in a day, and that's a lot as well. If I do any caffeine, It's never more than 300mg in a day.

need Apple to have a healthy market share to ensure a full selection of apps and accessories, and to keep Apple adding great new products.

Lorsque je démarre ma carrière en media.we sociaux sont une aide complète à savoir sur le information.As de mon connaissance est le meilleur livre de la marque sociale.

The bad news about caffeine is that long term use causes atrophy of hippocampus, which disturbs functions depending of this part of brains, like long term memory and learning ability.

Caffeine also accumulates in the body using a very neat modus operandi. A caffeinist has caffeine and its active metabolites in the blood all the time. This keeps also the stress hormone level high around the clock. Stress hormones constrict blood vessels and elevate the blood pressure in kidneys, which inhibits kidneys capability to secrete uric acids from blood to urine. Uric acids start to crystallize in tissues where the flow of water is slow, for example, bone, cartilage, fat etc.

Caffeine alters your renal function so that your kidneys cannot extract its toxic metabolites from your body.

These toxic metabolites affect the body on systemic level through chronically elevated stress hormone levels. Stress hormones speed up cell metabolism which ages the cells and shortens their lifespan. This, together with body acidity which is a superb breeding ground for bacteria, viruses, fungi, etc, causes around 80% of all chronic illnesses, both mental and physical.

I have studied this phenomena for 10 years, cured my caffeine based ms-symptoms, depression, anxiety and panic disorders. Now I advice others who are smart enough to try to get back of what's left of their health after using their bodies as a dump for toxic waste materials for decades. Check my blog if you want to get some real scientific knowledge about this addictive drug.

I'm not against the agree with the things you suggested.I would like to convey my admiration for your generosity in support of men and women that have the need for help with this particular concern. Your special dedication to getting the message all over had been wonderfully productive and have all the time made professionals much like me to attain their dreams. Your own invaluable tutorial means a great deal to me and additionally to my office workers. Thank you; from everyone of us.

Caffeine alone => adrenal fatigue? Source please anyone?

By PoopyPants (not verified) on 17 Feb 2012 #permalink

Hey Dave; Here is some study results on drinking coffee

Come over for a cup.


By Joan Beck (not verified) on 20 Feb 2012 #permalink

This is what I call a very interesting article. Especially for the majority of Portuguese who, just like me, are coffee-addicted, it is good to know that the consumption of caffeine prevents diseases like Parkinson and type II diabetes. I do not mention the "awful" withdrawal symptoms when you cannot find an open cafeteria to get your daily expresso...because it rarely happens here!
Anyway, I do believe the benefits of (moderate)caffeine consumption largely exceed the disadvantages.

By Cecilia Antao (not verified) on 11 Feb 2008 #permalink

Thanks everyone! I'm planning a future user's guide for nicotine, although that topic is pretty politically incorrect (it's difficult to get IRB approval to run studies on cognitive effects of nicotine, as the press can be bad).

Two questions:

1) As someone with a long history of UTIs before I lost the infected kidney causing most of the problems, I was cautioned by everyone with an opinion and a mouth to express it against stressing the remaining kidney with caffeine. My other kidney is functioning fine and my doctor told me to take no special precautions other than to drink plenty of water. I know many other common substances, such as certain foods and cold medicines, also have a diuretic or UT irritant effect. Is there some other, different effect of caffeine that I should be aware of?

2) I had heard (never mind from where) that it's a hacker trick to drink grapefruit juice to slow the metabolism of caffeine. Does this work? What's the chemistry involved?

Thanks :)

By speedwell (not verified) on 11 Feb 2008 #permalink

Hi Speedwell - As for #1: I'm just a brain guy, I know next to nothing about liver/kidney function.

As for #2: Grapefruit contains the flavonoid naringin, which does appear to slow the metabolism of caffeine. I'm going to update the post with this information - thanks!

Excellent. Generally informative and personally useful.

Caffeine is a DRUG. Like every single drug that is ever taken, it has desired-effects and it has side-effects. It is so great to read something that looks at both sides without taking a moral position.

Not only should you next tackle nicotine as hinted above, but why not also a genuine unbiased look at the benefits and costs of cocaine, heroin, cannabis?

Coming off caffeine isn't so hard.

Stop drinking coffee and take one or two 50mg caffeine pills per day for 5 days. The pills (e.g. 'proplus') are available in drug stores without prescription. This method completely eliminates the headaches, however you may be slightly drowsy for the first 2 days, so plan for early nights.

TRTRTR - Anecdotally I'm inclined to think that caffeine withdrawal is strongly genetic (the study linked above estimated complete heritability, but is based only on twin interviews) since I've never experienced withdrawal symptoms. Maybe proplus is good enough for you but not others...

Having tested a variety of nootropics, caffeine is clearly the best, especially in conjunction with lots of B vitamins and taurine.

By Brian Mingus (not verified) on 11 Feb 2008 #permalink

Great post! I encourage the nicotine one -- particularly if you have tips on ways to get it that negate health (and financial!) risks.

About grapefruit juice, though -- I've seen studies like this one by Maish et al (1996) that find no effect on caffeine. I think the jury might still be out on that.

Three cheers for caffein-- I hate to think what would happen to academia without a steady supply. If you can trust the "caffein meter" on the side of my tea box, drip coffee has about 90 mg/cup, black tea has only 30 mg/cup, and green tea even less, at about 20 mg/cup-- so green tea might not be ideal unless you want to drink 10 cups! I think I'll stick to my technique of nursing 16 oz of coffee for most of the morning, with a second cup in the afternoon if things get desperate. 200 mg/hour (2 + cups of coffee) seems excessive though-- even as a major coffee fan I don't think I could handle that much on a long-term basis.

Fantastic post, Chris. I just want to add a little warning: people who suffer anxiety disorders can have increased anxiety from caffeine, and too much caffeine can also disrupt sleep patterns. Do you have any info on chronopharmacology, timing and adjusting doses of caffeine to optimize sleep and social rhythms? (Maybe Bora does?) Other than the commonsense advice not to have espresso (or caffeine gum) too close to bedtime. :)

By Sandra Kiume (not verified) on 11 Feb 2008 #permalink

200mg per hour? You're sure you don't mean 20mg? 200mg is a LOT for many people. 400mg is already considered an overdose with intoxicating effects. Medical prescriptions for caffeine usually consist of 1x200 or 2x200mg for adults, per DAY. 200mg per hour will result in serious side effects, jittering, and caffeine addiction. I hope you're not serious in recommending this. Keep in mind some people are sensitive to caffeine and will experience insomnia after a single dose of 100mg. I don't want to imagine someone taking 200mg/h for several hours in that situation. You may be sending people for a quick trip to the hospital here. The only situation anyone could safely consume that much caffeine is when they are already seriously addicted and have build a very strong tolerance. In which case I'd recommend stopping with it altogether, unless you like peptic ulcers or esophagitis.

Great post. If you do a follow up, I'd like to see some info on how the active ingredient in Guarana differs from caffeine. I've heard its similar to caffeine chemically but stronger, but the details seem murky..

I'm a physics grad student, and it seems like I'm the only one that doesn't drink coffee at all. I never started, really.

Do you think that this negatively affects my performance? I have a hard time just sitting down to study.

JJK - Who knows whether you are worse off than your caffeinated peers, but *your* performance could almost certainly be "improved" with caffeine (with the definition of "improved" being subject to guideline #2 above).

As brian said, it's the world's most tested cognitive enhancer.

Hey for the kidney guy, I just wanted to let you know my nephrologist and others have warned me strongly against using grapefruit juice as it affects kidneys somehow. I have Dent's disease (kidneys) and have never understood why grapefruit, because lemons are supposedly really good for kidneys. Its all citrus.

Watch out.

Ive taken 600mg in a sitting and washed it down with a cup of coffee. Ill feel a little something off of that. Im what you'd call high tolerance I guess.

Hi, interesting article, although it seems to miss one area that is touched on in comments #19 and #20 - whether cognitive effects are actually above baseline, or are simply reversal of previous withdrawal (e.g. overnight abstention due to sleep). A growing body of evidence from the department I work in is suggesting there's little to no net benefit of caffeine over someone who does not consume:

Hi, intriguing post! But not reassuring enough to get me hooked on caffeine. I, for one, am *very* sensitive to caffeine (as opposed to theine), and just a little bit can cause loose bowels. My husband is always complaining about loose bowels, and I tell him that if he cut back on coffee consumption, he'd no longer have that problem.

But he does heavy intellectual work, and he needs the sitmulation. I echo the post immediately above: why don't you look into Guarana?

"Despite the huge variety of sources of caffeine - including caffeinated soap, candy, and of course chocolate"

Chocolate does not actually contain caffeine. It contains a similar chemical called Theobromine.

Great post, though.

The best coffee is Greek/Turkish with a glass of water. I experienced my first sixty years ago in the Middle East.

By robert painter (not verified) on 12 Feb 2008 #permalink

I find it very interesting that anyone would recommend 200mg of caffeine per hour!!! I love the taste of coffee personally, and I don't think I've gone a day without it for the past 10 years... but even I wouldn't drink that much!! I have anxiety and heart palpitations when I drink more than two cups of coffee in a day as many people would...caffeine reaches its maximum levels in the blood between 15 minutes and two hours after consumption, and its levels are reduced to half within three to seven hours. It has complex effects on the heart and arteries and can produce an abnormally fast heartbeat. The chemical relative theophylline is found in tea and is somewhat more potent than caffiene but tea only contains trace amounts. Brewed coffee contains more caffiene than brewed tea because there is more weight extracted from coffee than tea. I would also like to point out that you should consider how you brew your coffee as well for optimal taste: the water you use should be at a neutral pH, and if you care about the degree of roast of your coffee, medium has the fullest body, and robustas contain more caffeine than arabica.

By Shannon Dernesch (not verified) on 12 Feb 2008 #permalink

I am enjoying a cup of green tea right now. The caffeine keeps me awake after lunch and gets me through the rest of the day.

By Tech Deck (not verified) on 12 Feb 2008 #permalink

Every morning I make four shots of espresso and pour them into a 32oz Nalgene bottle filled with ice. (I then add a little extra water to fill it completely.)

I'd love to be a coffee purist and only drink it hot, but hot coffee has to be consumed within a short window of time. Iced espresso, however, can be sipped throughout the day while maintaining its flavor and temperature. This is the best way for me to keep caffeinated throughout the day without a peak.

Unsurprisingly, caffeine research has a long history. This short article talks about a 1907 caffeine study that was one of the first to use a double blind study design.

I am always impressed that all the effort and $$$ of the PharmaBiz has yet to come up with a cognitive enhancer better than good old java. Score one for the plants.

By PhD Scientist (not verified) on 12 Feb 2008 #permalink

Great post, thanks for putting that together!

I don't drink, don't smoke (anything), don't do drugs...I do have moderate persistent asthma, and I drink usually three cups of espresso per day. I've heard there is something in the coffee that relaxes bronchioles, but I'm not sure.

I'll keep this addiction. It's so tasty! And it helps me paint.

An addictive substance that's good for you and tastes good. What a concept! I knew there was a good reason for coffee being classified as a food group all by itself. (So is chocolate, for that matter.) :-)

By themadlolscientist (not verified) on 12 Feb 2008 #permalink

If you'd read the abstract of the Diabetes article you linked to, you'd find that it's not the caffeine that may reduce the risk of Type II Diabetes, but rather some other compound. They found that the reduction in risk is similar for decaf and regular coffee.

Great article, I really appreciate the links to all the various reports. What have you heard as regards caffeine and ADD? What little information I have found on the net has been contradictory. Also, when we talk about CUPs of coffee, remember that different people have different deffinitions. The coffee industry uses a 6oz. or 7oz. cup, cooks are familiar with the 8oz. cup, and Starbucks' tall "cup" is 12oz. Also cheaper coffee, such as Folgers and Maxwell House generally include robusta coffee in their blends which has a higher caffeine content than the more common arabica variety. Finally, if you are buying coffee at a coffee shop, they will generally brew stronger than most Americans do at home, and will therefore have a higher ammount of caffeine.

By Sheltron5000 (not verified) on 12 Feb 2008 #permalink

Great post. Good point made about caffeine withdrawal being different for everyone. I can go without a cup of coffee with no problem. But when told to eliminate white sugar from my diet for medical reasons for a few weeks, the withdrawal symptoms were horrible. Talk about a drug!

By Coffee, no sug… (not verified) on 12 Feb 2008 #permalink

heat, don't forget heat... caffeine loses punch after about three minutes of heat... so plan accordingly

Studies from US military show sleep deprived soldiers given coffee/caffeine to be equal (or, in a few, caffeine is better) than those given 'provigil'. The Us military was examining provigil as the modern amphetamine equivalent, something which would allow soldier to stay awake and shoot accurately. And, to their surprise, cffeine continually preformed equal or better. If desired will return w/ links.

You state: "Otherwise, why not enjoy a cup of green tea (coffee-flavored, if you must), as the Chinese have for nearly 5000 years? It's hard to come by a better longitudinal study than that."

Well, umm, no. That argument is a version of Argumentum ad Antiquitam ( - just because something is ancient, one can't assume it's necessarily good/beneficial or anything close to a study. As is often repeated, the plural of 'anecdote' is 'anecdotes' not 'data'. Plenty of ideas that are really bad for people (religion comes to mind... see "Breaking the Spell" by Daniel Dennett) survive *despite* being very bad for people.

Michael (#36), point taken, BUT if you'd read the abstract, you'd know they didn't show it was or wasn't caffeine as you claim (instead, they found n.s. differences, meaning that there could have been a difference which they failed to detect.) Furthermore, there is still caffeine in "decaf." Snarkiness notwithstanding, I've updated to link to a study showing a risk reduction at higher levels of coffee consumption, and made the old link a c.f.

Michael Meadon, thanks for the little lesson in science, but I was being light-hearted. way to miss the point.

When did we suddenly need to be "optimally wired"? When did we become such a nation of pantywaists that we cannot function in the day without stressing over caffeine levels and energy drink garbage?

People plowed fields 14-hours-a-day and never worried about this crap. What a bunch of wussies we've all become.

swag --
Please see Michael Meadon's comment two up from yours. Just because something is old doesn't mean it's a good idea. (

Anyway, who's stressing? "Learning new information" isn't the same as "stressing".

#45: You're talking apples and cheeseburgers. This article is talking about being optimally wired for cognitive work. If I had to plow fields 14 hours a day, the last thing I want is to be more perceptive of the fact I'm stuck plowing a field for 14 hours and probably don't need much to keep me energetic. On the other hand, if I'm stuck reading through tab after tab of code and excel files trying to figure out what someone did to mess up their data (as I usually am), I'm glad I have something that both keeps me awake and helps me stay on task in figuring out what I'm looking at.

I just remember someone telling me that there's a genetic test available that can determine whether you have genetic variations making you more vulnerable to cardiovascular toxicities - like heart attack - after consuming caffeine. As an avid coffee drinker, I ought to go take it...

anyway here are a couple links I just found re the polymrophism:…

By coffeegoose (not verified) on 14 Feb 2008 #permalink

Reading this almost makes me feel like I'm missing out on something - since I never liked the taste of coffee and hence never drink it, all while barely getting awake in the morning and feeling mostly tired throughout the average work day.

I'm wondering ... in your experience, whats the difference in potency between coffee and coffeinated soda, say regular Pepsi or Coke (of European origin, if that makes a difference)? Of course I can compare the raw coffeine figures myself, but maybe there's more to it than comparing raw numbers of one substance?

How would any coffee drinkers here who describe effects of coffee rate that vs. the effects of an equal amount of Pepsi/Coke/etc?

I'm really wondering, based on some of the accounts here about the "wonders" of coffee, if it would be beneficial for me to find some flavor or mixture or something of coffee that I could drink without being repelled by the taste.

So far I viewed caffeinated sodas as some sort of substitute but never really noticed any of the "alertness" or "wake-enhancing" effects described here - in fact I can drink a liter or more of these (or also tea) and barely notice any effect (can even sleep without problems very shortly aferwards).

The cognitive advantages of coffee may be enhanced for those of us who are "slow metabolizers." Unfortunately, coffee also seems to raise out risk of heart attack - while it *lowers* it for fast metabolizers. See this article for slightly more information:…

Also, people who plowed fields for 14 hours a day drank *plenty* of coffee. For example, just after the Civil War, freed slaves who became sharecroppers largely lived on white flour, fatback, and coffee -- leading to all manner of nutritional deficiencies. Remember all those stories about lumberjacks who stirred coffee with their thumb, Yukon golddiggers who could cut coffee with a knife, and "cowboy coffee"? People have been drinking serious amounts of coffee for a *long* time in the U.S.

By Meg Muckenhoupt (not verified) on 14 Feb 2008 #permalink

Such Non-Science, where does one begin. No mention of the depression caused by caffeine abuse, high blood pressure, insomnia, disrupted sleep, stomach problems, anxiety and
addiction. Brown fluids such as coffee or any other caffeine-laced fluid has NEVER been scientifically shown to cure ANY disease or illness. It's like saying red wine is good for the heart, nonsense, it's the grapes that are good for the heart. Good luck in your propaganda agenda.

By Kevin Kirk (not verified) on 14 Feb 2008 #permalink

#51: Ironic; you scold me as "nonscientific" for not mentioning various facts about caffeine (sorry, this isn't my day job), but then you make a claim that's contradicted by at least three different scientific studies. I don't have an agenda, but it sure sounds like you do!

Very intelligent piece, and useful as well.

Charles Darwin lauded 'yerba matte', a holly leaf product, as the finest stimulant known and I must concur. Most cities with south americans about will have it, and the gourds and siphons necessary for its proper preparation. Boiling hot is a requirement.

#52 Ironic; you scold #51 for his comments, and yet have thus far failed to address the issues raised in #24, that is, that caffeine does not necessarily 'optimally wire' *anyone* above the baseline levels that a non-caffeine drinker has.

TDD: If I could solve the baseline issue then I'd be writing a research article, not a blog post.

Nonetheless, some of the studies I've linked to use caffeine consumption as a covariate, others required long durations of caffeine abstinence, and yet others took baseline saliva samples of caffeine. Many of them discuss your lab's work related to withdrawal effects and conclude they are a relatively minor source of variance.

You could be right, but I am not an expert, and so I'm just going by the majority opinion in the studies I've read.

Interesting. I teach people how to remove this substance from their lives to improve it and your post teaches them how to maximize their potential through tips on it's consumption.

I'm not against your post at all, I'm more curious about how many people can approach the subject from different angles.

What do you guys think of 5 Hour Energy? I always buy a pack of these for a long road trip. I usually end up having one bottle, I stay awake for a couple hours, then crash. Which is really weird because the commercials claim there's no crashing. Maybe I'm doing it wrong?

Actually, I tend to crash a lot in the early afternoon, coffee or no coffee. Do you think 10mg of Prozac could have something to do with it?

Grapefruit interferes with the body's cytochrome P-450 pathway which is what is used to metabolize most drugs. By inhibiting this pathway, drugs will breakdown slower, thus maintaining higher levels for longer periods of time.

CHCH, re: your upcoming nicotine article, could you discuss the nicotine lozenge? All the literature says to stop taking it after 12 weeks. Are there real potential longterm health drawbacks or is that just what their trials were set up for? Is it gonna mess my gums up if I take one every day indefinitely? I need my teeth...

P.S. the lozenge beats the hell out of the gum & patch. Dunno about the inhaler. I'm beginning to think it beats cigarettes too, b/c it's a uniform dosage rate, instead of a spiky 1 cig/2hr. Plus, you don't stink.

Why bring coffee in to it at all? My friend rose was given a 1-kilo sack of pure caffeine for xmas, ordered from an English chemical supply house for about 40 euros (and as an aside, why do cocaine smugglers bother to go through all this folderol about swallowing balloons? Our bag full of white powder came through the mail to Australia perfectly well).
That means, in theory, that we can add caffeine to anything, at the rate of 200mg/hr (I did get her some centigram-accurate scales to go with it, just in case). The only problem is that caffeine is fairly bitter - you certainly can't just eat it off the spoon. So far we've gone OK adding it to marzipan, but that's rather fattening (though it does fit the added sugar line in (3)). Do you have any advice about cooking with caffeine? Is the effect destroyed by long heating? Not in coffee, obviously. You could sprinkle it on curry, I suppose, or substitute for asifoetidia (sp?). Brownies? Honey & lemon? Kaluha?

It is not the caffeine per se that has any alleged health benefits, it is the antioxidants in coffee as that is the major source of American's antioxidant intake due to their poor diet.

The major problem with caffeine is it promotes a surge release of noradrenaline (brain version of adrenaline) which gives a burst of energy. However, this surge DEPLETES its precursor, L-phenylalanine, thus promoting the eventual crash or letdown. A superior and healthier way to optimize caffeine intake than the "cycling" suggested by this article is to provide the brain with the raw materials it needs to make noradrenaline (L-phenylalanine, Taurine, Glycine, some vitamins & minerals) along with the caffeine for sustained energy levels throughout the day.

As with any source of continual stress, chronic intake of caffeine may eventually cause adrenal fatigue or shutdown in presence of suboptimal nutrition (i.e. not supplementing).

Fascinating post, even more fascinating comment discussion!

It's late now. Will wait till tomorrow for my next cup of coffee...

Has anyone done research on caffeine use in children? In my community, energy drinks are being used by kids as young as 5th grade, with their parent's knowledge. On a recent field trip, I saw some kids consume as much as four Rockstars in one day.

You can't kill the taste with Diet Coke, either.

I am interested in researching Guarana and caffeine in dietary supplements and energy drinks - if anyone could contribute, please go here.
My purpose is to understand and educate. Thank you for this post and helping get the word out about caffeine and our dependency on this.

Re: # 61

Any sources on that, MachineGhost? And what foods are good dietary sources of L-phenylalanine, Taurine, Glycine, etc?

Anyone use B12 energy drinks? These work wonders for me, way better than caffeine. It's how the "5 Hour Energy" drink advertised late at night works (the drink I use is ZipFizz). No crash, and improved concentration.

I wish there were more health drinks with caffeine, it seems like most caffeinated beverages are bad for you. Soda, coffee, energy drinks, the only drink with health benefit is green tea.

interesting post. I love caffeine.

This convinced me to sign up for your RSS feed. Well done! :)

How do I translate milligrams of caffeine? This article is clearly written with the layperson in mind, why give an arbitrary number without providing a translation into real-world cups of coffee, tea, hershey bars, etc. Also, this is the second article I've read that mentions Nicotene potentiating caffeine absorption without going into this interesting fact in any detail (the last article was a National Geographic article on coffee).


One trick I use, which I found in a study (can't find the reference at the moment, sorry!):

Have a cup of coffee, followed by a 15-minute power nap. No more, no less. The nap reduces the impulse to sleep while the caffeine gets absorbed in the system... The study found that the optimal effect is gained with a 15 minute nap.

I find I feel groggy after 15 mins, have to set the alarm, but that goes away fairly quickly and I'm left feeling better off than before. ;)

Coffee addict speaking.
I have recently lived in Australia for 6 months.
Where I was, you could only buy Ozgrown Coffee.
I really noticed the difference. In the UK I always sup
JAVA. It is for me personally the most potent waker-upper.
The brain performance enhancement that it seems to poke for me is that leftbrain/rightbrain interaction.
I just get more Eureka moments on Java.
I would say nicotine enhances problem solving in text but I am lucky enough to be unaddicted to that.

By jean cave (not verified) on 01 May 2008 #permalink

I cannot drink coffee partially due to the acid and the other part due to a subconscious mental association with a coffee overdose I had many years ago (when I was young and didn't quite grasp that you don't make instant coffee like you do instant iced tea-- four tablespoons of instant coffee later... I was very, very sick.)

I've had some success with sweet tea, and every so often an ice cold coca cola, but more often than not I end up feeling far, far more tired and worse from the sweeteners and sugars. This is likely due to my high metabolism.

I deal with nearly constant fatigue every day, from when I awaken until when I sleep, and so the times when caffienated drinks help me feel awake are precious as it allows me to be creative and motivated (I'm an artist), as well as increasing my fine motor skills and coordination.

I hope they'll do more research into figuring out optimal caffiene cocktails for different kinds of people. I sincerely doubt they'll find a one-fits-all dosage.

By S. Duranjaya (not verified) on 09 Jun 2008 #permalink

Reply to "score one for the plants":
As for pharmacies coming up with a better cognitive enhancer than caffeine, they certainly have done so; however, none is available without a prescription or otherwise obtained legally. I sometimes wonder about the people who I know who are functional and quite successful on these illegal substances. Is there success partially attributable to the fact that they are able to work longer than anyone else? Those who I know include partners in consulting and law firms, politicians, and investment bankers. Keeps Colombian farmers in business, I suppose.

it is good to know that the consumption of caffeine prevents diseases like Parkinson and type II diabetes.Not only should you next tackle nicotine as hinted above, but why not also a genuine unbiased look at the benefits and costs of cocaine, heroin, cannabis,this is a very useful article and people can get information from this.

Obstructive sleep apnea is a health problem that is seriously damaging the health of as many people as diabetes, heart disease or cancer does. In the US 16 million people have been diagnosed with obstructive sleep apnea but it is believed the number suffering but undiagnosed is a multiple of this.

Typically the undiagnosed rely on caffeine to manage their days. I wonder how many posters that rely on caffeine have obstructive sleep apnea? I bet more than 70%.

By Sleep Apnea Sufferer (not verified) on 17 Jan 2009 #permalink

Caffeine is a drug that is naturally produced in the leaves and seeds of many plants. It's also produced artificially and added to certain foods. Caffeine is defined as a drug because it stimulates the central nervous system, causing increased alertness. Caffeine gives most people a temporary energy boost and elevates mood.

Caffeine is in tea, coffee, chocolate, many soft drinks, and pain relievers and other over-the-counter medications. In its natural form, caffeine tastes very bitter. But most caffeinated drinks have gone through enough processing to camouflage the bitter taste.

Teens usually get most of their caffeine from soft drinks and energy drinks. (In addition to caffeine, these also can have added sugar and artificial flavors.) Caffeine is not stored in the body, but you may feel its effects for up to 6 hours.

Caffeine is the most important chemical in coffee. It is an odorless and slightly bitter solid. Caffeine mostly affects the brain, kidneys, and the cardiovascular (heart and blood vessels) system, but it also increases metabolism and breathing. A five ounce serving of regular coffee contains about 90-125 milligrams of caffeine; whereas, an equal amount of tea only contains 30-70 milligrams of caffeine. A soft drink only has about 37 milligrams of caffeine per five ounces.

Coffee has several effects on the human body:

* it helps to increase circulation of the blood
* it can cause nervousness and loss of sleep when taken in large amounts
* it can speed up a person's thoughts
* it produces a feeling of well-being
* it gives some people the ability to memorize simple numbers, concepts, and thought sequences easier

If you drink one or two cups several times a day, coffee will have little effect on the cardiovascular system. However, if you drink three to four cups several times a day, it will slow your pulse rate, raise blood pressure, contract blood vessels that are right under the skin, and dilate blood vessels of the kidneys, muscles, skin, and heart. Finally, caffeine makes the heart contract harder while it's pumping.

I am sitting here suffering from caffeine withdrawal (I'm on my fourth day of no caffeine) and ran across this blog. . . I gave up caffeine thinking it would help me. I suffer from mild depression, migraines, and constant agonizing sleepiness. I sleep well at night . . . usually 7-8 hours, but the mornings are impossible, and I rarely feel wide awake or energetic. I used to down coffee and coke all through the day, but I was having bursts of energy followed by these painful crashes where I'd literally have to lay my head down and sleep wherever I was (even at work!) Giving up caffeine seemed the logical choice to what I've been battling, but I am wondering now if I made the right choice. I currently have a headache that could move mountains (not a migraine - just a horrible headache.) For the last few days, I also have not been able to focus at work, nor can I stay focused for my son in the evenings when he needs my help on homework. . . it seems like taking myself off of caffeine has hurt more than help!

Which coffee brand (Maxwell House, Folgers, etc.) contains the highest (or strongest) caffeine content? Defined by msg's per once, that you can buy at the local Krogers or local grocery store?

By eddie rankey (not verified) on 20 May 2009 #permalink

It's good to not drink caffeine after 12:00 noon. In the morning, your adrenal hormones such as norepinephrine, adrenaline, thyroid hormones etc. So caffeine being an adrenal stimulant matches this hormone profile. However, as the day gets later, your body produces healing & sleep hormones such as HgH, serotonin, melatonin, etc. You do not want to fight this by drinking caffeine in the afternoon. Doing this along with drinking too much caffeine everyday can cause adrenal fatigue. If you want to learn more about nutrition, visit my site at
-Ravi Jaya

Excellent article. I am currently living in South America and drinking coffee starts at 2 years old here, I have a step daughter who is now 11 and has been drinking coffee her whole life until now as I told her she will need to wait till she is older as I do believe that coffee makes it difficult to connect with your inner source or to use your brain properly. I do drink it still but I do notice the difference. Again thanks for the article.

Kris Kelly

In the past few months we have been buying
Maxwell House (canned) ground coffee (caffeinated,
regular or dark). This may be a coincidence
but we have both had nap attacks in the afternoon.
I wonder if there has been a manufacturing
error in the coffee.

Thank you.


By Mmmousemaid (not verified) on 31 Oct 2009 #permalink

I deal with nearly constant fatigue every day, from when I awaken until when I sleep, and so the times when caffienated drinks help me feel awake are precious as it allows me to be creative and motivated (I'm an artist), as well as increasing my fine motor skills and coordination.

I deal with nearly constant fatigue every day, from when I awaken until when I sleep, and so the times when caffienated drinks help me feel awake are precious as it allows me to be creative and motivated (I'm an artist), as well as increasing my fine motor skills and coordination.

i have to say this is the first time i visit this site and i also have to say that it will not be the last time.. thanks for post such a knowledge of caffeine that i have to have it everyday. now i know how does it work to my body, good and bad thing about it...:)

Great study! I do love my caffeine. Knowing how to use it to optimal effect is good information. Im actually going to try 200 mg per hour.

In the past few months we have been buying
Maxwell House (canned) ground coffee (caffeinated,
regular or dark). This may be a coincidence
but we have both had nap attacks in the afternoon.
I wonder if there has been a manufacturing
error in the coffee.

Thank you.

I think a moderate amount of caffeine can help in the short term - but it does come at a cost. For one, it can be addictive. And while it does have some beneficial effects, the opposite is also true.

Second, most sources of caffeine that people consume are full of sugar. Starbucks, chocolate bar, candy and so on. Fact is, caffeine in itself is bitter and few will consume it for little energy it provides.

Try a quick nap or a short walk when you're feeling down. It's your body's way of asking for a break.

Hmmmm, these kind of studies make me a bit weary. This often gives people the idea that using caffeine as a substitute for actually rest and exercise for increasing energy. This can lead to very unhealthy, out of shape people.

Hi Peter - In fact most of them do take that into account; I try to only describe the most rigorous studies as a matter of principle.

It would make sense that grapefruit juice helps keep caffeine in the blood stream for longer because it is an inhibitor of the cytochrome P450 complex. Caffeine, like other drugs (prescription), are broken down by the cytochrome P450 complex and thus inhibiting of such complex leads to the breakdown process taking longer.

For reference, haven't you ever wondered why prescriptions say to not take with grapefruit juice? It can cause toxic levels of the drug in your system... thankfully caffeine isn't toxic :)