Using caffeine intelligently

or A Cognitive Scientist Talks About Caffeine

I am not a pharmacist, and I am certainly not a doctor. I didn’t even stay at a Holiday Inn Express last night. I am, however, a big fan of caffeine, and the recipient of a four year honours bachelor of science degree in Cognitive Science and Artificial Intelligence, so I know a thing or two about minds. Because using caffeine (or any stimulant for that matter) is largely a mental affair, and because we are on the internet, I feel this adequately qualifies me to prattle on for some length.

My goal in writing this is to help people use caffeine more effectively by helping to understand its effects. But there are a lot of things that are not my goal and it is only fitting to discuss them right up front. I’m not trying to start a debate about whether caffeine has long term health effects. Because it is a nice thing, it has perforce garnered plenty of accusations that it causes limbs to fall off and hair to grow where there wasn’t hair before, and so on. That is a discussion that is best left to properly conducted, properly controlled, long term studies, but as a quick and by no means comprehensive review…

Likewise I’m not going to go on about how it seems to reduce the risk of Parkinson’s Disease and prevent skin cancer, liver cancer and others. That is for another discussion, but suffice it to say that even if it weren’t a stimulant it might be worth taking strictly for the health benefits.

Understanding Arousal

There is a law in cognitive science called the Yerkes-Dodson law. Like any good law, it has a graph:

Yerkes-Dodson Law Graph

What Yerkes and presumably Dodson found is that for most cognitive endeavours, human beings perform differently depending on their level of physiological arousal when performing it. And, perhaps counter-intuitively or perhaps not depending on how you intuit, this is not a linear relationship but an inverted-U one. When we are at a low state of arousal, we perform poorly. As we wake up and get more energized by one thing or another, we perform more competently (faster, smarter, fewer errors, etc) up to a point, after which further arousal actually impairs performance. This is where the phrase “over-stimulation” comes from, and it’s not just a term for hyperactive toddlers.

Your level of physiological arousal at a given time is the product of a large number of factors, more than you might think. Obviously, things like fatigue reduce your arousal level, and things like a gun being pointed at you while rabid monkeys inject adrenaline right into your heart like in pulp fiction when that girl was overdosing and then John Travolta had to go to the red headed dope dealer who was the same guy as the meditating doctor on Chicago Hope and the NEEDLE WAS STICKING OUT OF HER CHEST, SWEET MERCIFUL MOTHER OF GOD — tend to increase your level of physiological arousal. Other things do too: noise increases arousal. Pain increases arousal. Stress increases arousal. Interestingly, solving a complex problem or puzzle increases arousal. Being ill decreases arousal, on top of any loss of arousal related to lack of sleep.

The phrases “extrovert” and “introvert”, as they are currently used in psychological literature, refer basically to a person’s basal level of… you guessed it: physiological arousal. Extroverts have low levels of in-born, always-on internal arousal, which causes them to seek more sources of stimulation from the world, to drag them up the Yerkes-Dodson curve towards optimum arousal. They are impulsive, they are loud, they drive fast and talk on the phone and smoke cigarettes. They bore quickly. See the pattern here? Introverts have comparitvely higher levels of physiological arousal by default. They like small groups. They are as likely as not to drive with NO music. In fact, they probably have trouble reading an article like this one with music playing in the background. Why? Because they are often already near the top of the curve, sometimes even past it, into overstimulation territory. They want quiet when they’re concentrating because too much background noise (literal or figurative) will reduce their efficacy. It’s a picture painted in blacks and whites, and most people will fall somewhere in the middle, but the argument is compelling — once you understand Yerkes-Dodson, you can understand these “personality types” (one might prefer to say “behaviour patterns” or “activation levels” these days) as being really just individuals attempting to maintain the good feelings that come from being at optimal arousal.

A gold star to the first person who can see where caffeine fits into this picture.

Managing Arousal with Caffeine

Caffeine, by definition as a stimulant, increases physiological arousal. What’s really nice about it is that unlike some other candidates, it is not particular habit forming. Caffeine withdrawal is a documented and broadly experienced phenomenon. But it also lasts about a day for most people, and usually consists of a headache. While a tolerance does build up to some of caffeine’s effects, the tolerance is not constantly rising as with, say, heroin, such that larger and larger doses are required to acheive the same effect. Most coffee drinkers, for instance, derive benefits from drinking their morning coffee that are consistent with yesterday’s benefits and tomorrow’s benefits. The nice thing about understanding physiological arousal is that it obviates the need to understand the complex neurochemistry of caffeine as an adenosine blocker — we can basically understand it pretty well as just a black-box stimulant.

It should be becoming clear to you that in order to use caffeine effectively, you have to use it in the context of your physiological arousal. If you are trying to study some topic far less engaging than cognitive science, and you feel yourself getting distracted and listening to the conversations outside your window, there is a strong indication that your arousal level is low and that caffeine will help get you moving and focusing and concentrating. If you are trying to study said material, and you are scanning back and forth between notes and textbook, furrowing your brow, and wishing your roommate would get off the phone so you could concentrate, you sound like someone who is already at or above peak arousal and coffee will not help, in fact it will probably make things worse.

Read it again if you have to.

Sometimes the intelligent way to use caffeine is not to use caffeine. It is a tool that does one thing (albeit a generalized and useful-across-many-domains thing): it increases your physiological arousal. It wakes you up when you’re sleepy. When you’re not sleepy, it can improve your mood, and make you more able to concentrate and quicker to think and react. But when you’re already at peak, it will push you over the top of the curve, you may get cranky, you may get unfocused, and you will almost certainly be less effective.

How Much Is Enough

The last step in using caffeine effectively is understanding your dosage and your sources. Knowing how much caffeine gives you nothing, how much gives you a lift, and how much gives you jitters is usually a trial and error process that most adults have already explored. I am a 230Lb, 6’5″ male and habitual moderate caffeine user, so a large cup of coffee, at 200mg, is only just enough to give me a small lift. I honestly don’t think I’ve ever had jitters or palpitations, even after several such doses. I have a coworker who is a 5’2″ female that might weigh 110lbs soaking wet, and she won’t drink a small coffee or sometimes even pop because it makes her “very hyper.” There is no good or bad level of sensitivity really, but understanding where you are on that scale is essential because once you understand that caffeine is a tool for tweaking arousal, you need it to be a calibrated tool. For me, a large coffee or caffeine pill is a good dose, it ups my arousal by a large enough amount to be significant, but a small enough amount that I can double or triple up if I feel it’s appropriate. My coworker can’t use “large cups of coffee” as her dose because it would take her across the entire curve far too quickly, but that doesn’t mean she can’t use caffeine. A cup of black tea has around 60-80mg of caffeine, a can of cola has around 40mg, and for the very caffeine sensitive, a cup of green tea has around 15mg of caffeine (charts abound).


Understanding caffeine doesn’t require neurochemistry. It really doesn’t even require cognitive science, since people have been using it pretty effectively for hundreds, if not thousands of years. But if you take the time to consider your own physiology, your state of mind, and your sensitivity, caffeine can be an extremely valuable tool for staying at the top of the curve whenever necessary. Obviously moderation is key, caffeine is lethal in doses of 10g or more, but that’s a perfectly obscene amount of coffee, and in moderate doses, even up to several hundred mg or more, it seems quite benign if not actually beneficial. But don’t listen to me, that’s what your doctor is for. I’m just a cogsci geek.

16 thoughts on “Using caffeine intelligently

  1. Great article – you should submit this for paper publication somewhere. I hope you keep up with this writing – you have an engaging and readable written voice, and you explain things very well. It wouldn’t surprise me to see your name on a bestseller list some day.

  2. You are too kind. I like being printed well enough – and the Make: experience has been a pleasant one (which is as I would have expected, but for Wil‘s complaints.) We’ll see where it goes, but so far this blog is just me looking for an outlet more personal than e2.

  3. Very cool article. I drink coffee by the gallon, drive like a maniac, and can only work with two or more sources of stimulation in the background. Not because i’m an asshole, but because I am am extrovert. Excellent news.

  4. Great stuff. Never occurred to me that I’m reducing efficiency by having another coffee. Sometimes you’re in that in-between state where nothing will help you get back to work, so you have the coffee anyway and space out.

    I need a new stimulant.

  5. Bad news for people who use caffeine daily or a few times a week: A person can develop a caffeine allergy and not know it, which causes ADHD, OCD, anxiety, panic, bipolar disorder, schizophrenia, PMS and a lot more. Most doctors don’t know about caffeine allergy either, so they just diagnose anything and everything.

    Moderation or none at all is key to safe health and brain function.

  6. Well, I’m not a doctor, but then again neither is the author of that book/site. I’m even willing to believe that caffeine causes an allergic response in some people because hey, lots of plant products do, and I don’t see why caffeine should be different, though it’s clearly a lot less common. That’s about where my agreement ends though.

    Call it ad hominem if you will, I prefer to think of it as a junk filter, but in either case, certain things tend to flag an argument as being, for lack of a better term, new age hippie bullshit, and really high on the list is people who talk about how the Dark Forces are trying to suppress their findings. Another big clue is when their research is supposed to explain a huge swath of maladies in one tight little package. Normally they are not so bold as to heap the laurels on themselves though, waiting instead for others to do it; I guess she was just in a rush when she penned lines like,

    “It took a fictional child to point out that the Emperor’s new clothes consisted of his birthday suit and not a thing more, but I’m not a character in a book. A quiet woman from New England, I was an above average student in high school. But my intellect depreciated when I lost 27 years, including recovery years, due to chronic allergic response, medical ignorance and caffeine, a legal psychoactive drug. Well, I am “back.” And thank goodness I am a medical technologist and know how the human brain and the other organs function. “

    Yes, thank goodness for that.

    If she’s on to something, if every psychosis and physical ailment is attributable to the action of this “ingestable poison” then I look forward to repeated replication of results in peer reviewed journals. In the meantime, let’s close with this, maybe my favourite of the black helicopters quotes:

    Before I wrote the book, I contacted all the “right” people; I called the FDA, the NIMH, and other federal and state agencies about my findings. But not one person listened, perhaps because most everyone ingests caffeine and caffeine has depreciated intellect and comprehension skills, or perhaps because people own stock in caffeine, or have an interest in the pharmaceutical companies.

    Yes! Curses! It’s all those people with their stock in caffeine! And the pharmaceutical industries! They’re an easy target! Except that none of them has any ownership of caffeine because it’s an easy to synthesize generic. One reason results pointing to its preventative effect on various cancers will probably never go through proper FDA trials is that no pharma company has an incentive to fund research into something that people can get in a cup of coffee – but SURELY they are somehow pulling the strings behind the curtain.

  7. Nice article, thanks. I love coffee, but I found the introvert and extrovert part interesting as well, having recently discussed it with a friend.

    It’s unfortunate that the “everything you consume is slowly poisoning you” contingent has to get involved, but thus is the internet.

  8. This article is very insightful. And this response isn’t bashing anyone. However, I would like people to be aware of the dangers that caffiene pills present. My best friend took “stackers” on a daily basis. She had taken them for years. Three days ago I went to her house to check on her. Everyone I knew had tried to contact her. She hadn’t returned anyone’s phone calls. My friend never answered the door. She had passed having an aneurysm. Because of these pills I will no longer see my friend. With the exception of the funeral on Wednesday. Please, before you take another pill consider how your loved ones would feel if you were no longer here.

  9. So… I’m curious. Is there a way to lower your arousal? What if I almost never need caffeine and almost always just need to lower my arousal? Should I have a beer?

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