What Caffeine Actually Does To Your Brain

For all of its wild popularity, caffeine is one seriously misunderstood substance. It's not a simple upper, and it works differently on different people with different tolerances — even in different menstrual cycles. But you can make it work better for you.

Photo by rbrwr.

Editor's Note: This was first published on Lifehacker Australia, and it's still incredibly relevant to Sleep Week, especially considering all those vodka and Red Bull's you'll be drinking tonight at the club. Perhaps you should read this first?

We've covered all kinds of caffeine "hacks", from taking "caffeine naps" to getting "optimally wired". But when it comes to why so many of us love our coffee, tea or soft-drink fixes, and what they actually do to our busy brains, we've never really dug in.

While there's a whole lot one can read on caffeine, most of it falls in the realm of highly specific medical research or often conflicting anecdotal evidence. Luckily one intrepid reader and writer has actually done that reading, weighed that evidence and put together a highly readable treatise on the subject. Buzz: The Science and Lore of Alcohol and Caffeine, by Stephen R. Braun, is well worth the short 224-page read. It was released in 1997, but remains the most accessible treatise on what is and isn't understood about what caffeine and alcohol do to the brain. It's not a social history of coffee, or a lecture on the evils of mass-market soft drinks — it's condensed but clean science.

What follows is a brief explainer on how caffeine affects productivity, drawn from Buzz and other sources noted at bottom. We also sent Braun a few of the questions that arose while reading, and he graciously agreed to answer them.

Caffeine Doesn't Actually Get You Wired

Right off the bat, it's worth stating again: the human brain and caffeine are nowhere near totally understood and easily explained by modern science. That said, there is a general consensus on how a compound found all over nature, caffeine, affects the mind.

Every moment that you're awake, the neurons in your brain are firing away. As those neurons fire, they produce adenosine as a byproduct, but adenosine is far from excrement. Your nervous system is actively monitoring adenosine levels through receptors. Normally when adenosine levels reached a certain point in your brain and spinal cord, your body will start nudging you toward sleep, or at least taking it easy. There are actually a few different adenosine receptors throughout the body, but the one caffeine seems to interact with most directly is the A1 receptor. More on that later.

Enter caffeine. It occurs in all kinds of plants, and chemical relatives of caffeine are found in your own body. But taken in substantial amounts — the semi-standard 100mg that comes from a strong eight-ounce coffee, for instance — it functions as a supremely talented adenosine impersonator. It heads right for the adenosine receptors in your system and, because of its similarities to adenosine, it's accepted by your body as the real thing and gets into the receptors.

More important than just fitting in, though, caffeine actually binds to those receptors in efficient fashion, but doesn't activate them — they're plugged up by caffeine's unique shape and chemical makeup. With those receptors blocked, the brain's own stimulants, dopamine and glutamante, can do their work more freely — "Like taking the chaperones out of a high school dance," Braun writes in an email. In the book, he ultimately likens caffeine's powers to "putting a block of wood under one of the brain's primary brake pedals".

It's an apt metaphor, because it spells out that caffeine very clearly doesn't press the "gas" on your brain, and that it only blocks a "primary" brake. There are other compounds and receptors that have an effect on what your energy levels feel like — GABA, for example — but caffeine is crude way of preventing your brain from bringing things to a halt. "You can," Braun writes, "get wired only to the extent that your natural excitatory neurotransmitters support it." In other words, you can't use caffeine to completely wipe out an entire week's worth of very late nights of studying, but you can use it to make yourself feel less bogged down by sleepy feelings in the morning.

These effects will vary, in length and strength of effect, from person to person, depending on genetics, other physiology factors, and tolerance. But more on that in a bit. What's important to take away is that caffeine is not as simple in effect as a direct stimulant, such as amphetamines or cocaine; its effect on your alertness is far more subtle.

It Boosts Your Speed, But Not Your Skill — Depending On Your Skill Set

Johann Sebastian Bach loved him some coffee. So did Voltaire, Balzac and many other great minds. But the type of work they did didn't necessarily get a boost from their prodigious coffee consumption — unless their work was so second-nature to them that it felt like data entry.

The general consensus on caffeine studies shows that it can enhance work output, but mainly in certain types of work. For tired people who are doing work that's relatively straightforward, that doesn't require lots of subtle or abstract thinking, coffee has been shown to help increase output and quality. Caffeine has also been seen to improve memory creation and retention when it comes to "declarative memory", the kind students use to remember lists or answers to exam questions.

(In a semi-crazy side note we couldn't resist, researchers have implied this memory boost may be tied to caffeine's effect on adrenaline production. You have, presumably, sharper memories of terrifying or exhilarating moments in life, due in part to your body's fight-or-flight juice. Everyone has their "Where I was when I heard that X died" story, plugging in John F. Kennedy, John Lennon or Kurt Cobain, depending on generational relatability).

Then again, one study in which subjects proofread text showed that a measurable boost was mainly seen by those who could be considered "impulsive" or willing to sacrifice accuracy and quality for speed. And the effect was only seen in morning tests, indicating the subjects may have either become lightly dependent on caffeine, or were more disposed to such tasks at that time of day.

So when it comes to caffeine's effects on your work, think speed, not power. Or consider it an unresolved question. If we're only part of the way to understanding how caffeine effects the brain, we're a long way to knowing exactly what kind of chemicals or processes are affected when, say, one writes a post about caffeine science one highly caffeinated afternoon.

For a more direct look at what happens to your brain when there's caffeine in your system, we turn to the the crew at Current. They hooked up one of their reporters to a brain monitor while taking on some new caffeine habits and share their brains on caffeine:

Effectiveness, Tolerance And Headaches

Why do so many patients coming out of anaesthesia after major surgery feel a headache? It's because, in most cases, they're not used to going so long without coffee. The good news? If they wait a few more days, they can start saving coffee again for when they really need it.

The effectiveness of caffeine varies significantly from person to person, due to genetics and other factors in play. The average half-life of caffeine — that is, how long it takes for half of an ingested dose to wear off — is about five to six hours in a human body. Women taking oral birth control require about twice as long to process caffeine. Women between the onset of ovulation and beginning of menstruation see a similar, if less severe, extended half-life. For regular smokers, caffeine takes half as long to process — which, in some ways, explains why smokers often drink more coffee and feel more agitated and anxious, because they're unaware of how their bodies work without cigarettes.

As one starts to regularly take in caffeine, the body and mind build up a tolerance to it, so getting the same kind of boost as one's first-ever sip takes more caffeine — this, researchers can agree on. Exactly how that tolerance developers is not so clear cut. Many studies have suggested that, just as with any drug addiction, the brain strives to return to its normal function while under "attack" from caffeine by up-regulating or creating more adenosine receptors. But regular caffeine use has also been shown to decrease receptors for norepinephrine, a hormone akin to adrenaline, along with serotonin, a mood enhancer. At the same time, your body can see a 65 per cent increase in receptors for GABA, a compound that does many things, including regulate muscle tone and neuron firing. Caffeine, it's been suggested, is probably not directly responsible for all these changes. By keeping your brain from using its normal "I'm tired" sensors though, your caffeine may be causing the brain to change the way all of its generally excitable things are regulated. Your next venti double shot goes a little less far each time, in any case. Photo by zoghal.

A 1995 study suggests that humans become tolerant to their daily dose of caffeine — whether a single soda or a serious espresso habit — somewhere between a week and 12 days. And that tolerance is pretty strong. One test of regular caffeine pill use had some participants getting an astronomical 900 milligrams per day, others placebos — found that the two groups were nearly identical in mood, energy and alertness after 18 days. The folks taking the equivalent of nine stiff coffee pours every day weren't really feeling it anymore. They would feel it, though, when they stopped.

You start to feel caffeine withdrawal very quickly, anywhere from 12 to 24 hours after your last use. That's a big part of why that first cup in the morning is so important — it's staving off the early effects of withdrawal. The reasons for the withdrawal are the same as with any substance dependency — your brain was used to operating one way, and now it's suddenly working under completely different circumstances. Headaches are the nearly universal effect of cutting off caffeine, but depression, fatigue, lethargy, irritability, nausea and vomiting can be part of your cut-off too, along with more specific issues, like eye muscle spasms. Generally, though, you'll be over it in around 10 days — again, depending on your own physiology and other factors.

Getting Out Of The Habit And Learning To Tame Caffeine

Beyond the equivalent of four cups of coffee in your system at once, caffeine isn't giving you much more boost — in fact, at around the 10-cup level, you're probably less alert than non-drinkers. So what if you want to start getting a real boost from caffeine once again, in a newly learned, less dependent way?

Our own Jason Fitzpatrick has both intentionally "quit" coffee, as well as just plain run out of coffee. Being the kind of guy who measures his own headaches and discomfort, he suggests measuring your caffeine intake, using caffeine amounts in all your drinks, chocolate and other "boosting" foods. Wise Bread has a good roundup of caffeine amounts, and the Buzz Vs The Bulge chart also shows how many calories you'll be cutting if you start scaling back. Once you know your levels, map out a multi-week process of scaling down, and stick to it. Jason also suggests that dependency kicking is a good time to start taking walks, doing breathing exercises or other mind-clearing things, because, in his experience, their effects are much greater when caffeine is not so much a part of your make-up.

Braun, author of Buzz, sees it the same way, but still uses coffee — strategically, according to our email exchange:

In practical terms, this means that if you'd like to be able to turn to caffeine when you need it for a quick, effective jolt, it's best to let your brain "dry out" for at least several days prior to administration. This is actually my current mode of consumption. I don't regularly drink coffee anymore (gasp).

This from a man who loved (and wore out) his home espresso maker. I love coffee in all its guises. But after 30+ years it wasn't working for me. For one thing, the problem with caffeine is that there are adenosine receptors all over the body, including muscles. For me, that meant that caffeine made me vaguely stiff and sore, and it aggravated a tender lower back that was prone to spasm. But I also just wasn't getting a clean, clear buzz from coffee...I drank so much, so regularly, that drinking an extra cup or two didn't do a helluva lot except, perhaps, make me a little more irritable.

So about a year ago I slowly tapered down, and now I have, if anything, a cup of tea (half black, half peppermint) in the morning. (The amount of caffeine from the black tea isn't enough to wire a gnat.) Not only does my body feel better now, my brain is clean of caffeine, so I really want (or need) a good neural jump-start, I will freely...nay, ecstatically...indulge. Then I stop and let the brain settle again.

That's the theory, anyway...and it's basically true, although I'll freely admit that sometimes I have an espresso or coffee just because it tastes so damned good.

That's our attempt at summing up the science and common understanding of caffeine in one post. There is, as you can imagine, a lot more to explore — Braun's Buzz is a good starting point, but you'll find your own way from there.

What's the most interesting thing you've learned about caffeine, either from reading or personal experience? Share the science in the comments.

Originally published on Lifehacker Australia

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    It used to wire me a lot more when I was younger. After a morning 20k ride and a couple of cappuccinos I'd be vibrating. Now I don't even feel it. I can have cup after cup and all it does is make me pee more and make it harder to get to sleep. But I can quit cold turkey without any problem. I just drink for the taste and the habit of making it.

    I have never really felt the effects of caffeine, but I do enjoy coffee very much. I start my day with a freshly brewed coffee and pipeful of full virginia flake, the flavours are a perfect match. I think it is the temperature of the hot coffee that gets me going more than the caffeine.

    without a doubt coffee affects me. when i stopped drinking it (and also eating a bit healthier) i slept better, lost some fat, and didnt suffer from energy crashes. i got sucked into drinking it again at the moment, and i really do feel like shit before i have a bit of coffee in the morning. possibly also to do with the sugar.

    Good article.

    I can confirm all what it says from personal experience and my background knowledge in bodybuilding in specific relation to steroid taking.
    It has been long established that taking steroids (any drug really) the body builds up a resistance/tolerance to it, and u either have to stop or take higher dosages to get the same effect/benefit.

    This is why steroids are taken in a cyclic nature (a few weeks on followed by a few weeks off).
    The break allows the body to heal itself after the 'nasties' as well as being ready and susceptible to the next round of steroids.

    An example of a non-steroid (yet enhancing) short duration cycle is the ECA stack (Ephedrine Caffeine Aspirin, http://en.wikipedia.org/wiki/ECA_stack). To use effectively you take for 3 days followed by 3-7 days off, repeat. Otherwise come day 4, 5 or 6 of being on you no longer feel the effects nor are the weightloss effects as prolific.

    Today i drink a real coffee (or pop a few caffeine pills, as high as 400mg) only two days a week (mon & fri). These are heavy labour/work days and I really enjoy the kick and alertness/energy it creates when i need it the most. Sometimes on those days i will have a morning coffee followed my an afternoon pill or two and find it really works helping to remove the sleepy, hazy, tired feeling allowing me to continue working at a higher degree (i literally go from being someone yearning for my bed to the energizer bunny).
    Indeed I have (in the past) drank a coffee (just one) every morning and started to notice the lack of a 'lift' in the morning (especially when i needed it most on those Monday's and Fridays).

    So it was obvious to me that i was building up an immunity to it, so i stopped for a week or two and resumed back to my mon and friday only (the rest of the week its decaf coffee).

    I hear so often from people that caffeine doesn't effect them, its a drug of course its gonna effect you, trying to explain just one coffee a day will stop you from experiencing the positive benefits (the 'lift') falls on deaf ears.
    And as this article points out the dosages don't have to be high, caffeine is in alot of goods, chocolate, tea, soda etc.
    It seems that frequency is the killer, not amount (dosage).

    What's curious is how long do you have to abstain from caffeine (coffee) to 'reset' yer body so that when resuming you can enjoy its benefits again.
    And how often can you have that coffee, still receive its benefits without overstepping and slowly losing its effects (optimal 'riding the wave').
    For a low end user like me twice a week still works, can i introduce a third day, or is that pushing it too far?
    I only needed 1 week (or 10 days or so) to reset my body to make coffee's work again, but then again i was only ever doing 1 coffee a day (i don't do chocolate, soda or tea). For those that are doing several coffees a day (as well as chocolate, soda and tea) does it take longer, are 3 weeks needed?

    Even when we look at the above example comments from Nathan and Jarod there is almost an 'opinion' of whether caffeine works or not. I'm sorry Nathan but caffeine does have an effect on you, its just been so long ago that you took it sparingly that you no longer feel any buzz whatsoever. Jarod says "without a doubt coffee affects me" implying for some people he accepts that caffeine might not work on them. Well it DOES, they have just built up tolerance to it. Its a little like saying "without a doubt alcohol affects me" or "without a doubt anaesthetic affects me", its kinda stating the obvious.

    What needs to be really understood, for those that still claim it (caffeine) doesn't effect them, is how little the dosage needs to be to be able to build up an immunity to it.
    Consider the first time you ever had a coffee (or started drinking coffee), think back, were you 13, 16, 20 years old? Did you start by having the occasional one or did you implement it daily from the get go? The last time somebody like Nathan (and i'm not singling you out lol) felt the effects might have been YEARS ago when he first tried it. Since then he has been numb to it (for decades perhaps) so concludes it doesn't work on him (like his genetics are special or summin).

    Coffee should be cycled. The end.

    Just my opinions but hey, i love reading other comments, so here are a few of my own:
    Coffee," ït doesnt affect me", "I can sleep straight after having one "...yes some do sleep shortly after, even me sometimes, BUT ONLY, if it is weak. Those who say it doesn’t affect them, well, IMO, they are not lying, just delusional - of course some respond to it more, but it does absolutely affect them. I hear that garbage all the time and i have so much fun watching these so-called non-addicted, non-affected people, starting to buzz and talk a lot more etc after having their dose.

    It’s so funny, I used to experience similar things whilst living on meth(ice) all day long for a couple of years. Of course you build immunity, but, indeed you are still affected. Having watched and interacted with hundreds of people on speed/ice/meth thousands of times, you just get to know what and how - BUT yes again I will say, different amounts affect different people in different scales.

    But back to coffee... I love coffee, and I only starting drinking it at 21, after living on marijuana all day everyday, BUT then when i had to get a job, yet still smoking all night every night, I needed a pick me up in the morning and didn’t actually realise its affects - oh, i loved it!!! - one triple espresso in the morning would last all day, making me alert, work fast, and well... over the years I have gone cold turkey twice, but I don’t care anymore, I will just drink it now as the benefits(at least the perceived benefits for me personally) far out way the disadvantages.

    One other very important thing for me at least, maybe not for others, BUT, at least for me is that I never read many books at all, indeed I hardly read anything until I found books onRupert Murdoch, Kerry Packer, Christopher Skase and then Stephen Donaldson’s books(two of at least and all of which I devoured rapidly) other than that, not much in the way of books other than study books. HOWEVER when I have coffee(a strong one at least) my vocabulary increases 10-fold, or at least the ability to bring it forth, cohesively, accurately, intelligently(and very very FAST too) seems to increase enormously and I find myself having the ability to talk and speak with others who I may ordinarily deem much more intellectual than I, at a minimum of their level and much greater at times... Indeed I seem to remember and recount innumerable facts that I have absorbed over the years that would ordinarily seem to be “on the tip-of-my-tongue” but never actually coming out my mouth, or if and when they do, they come in out in bits, unintelligibly, and loosely – in effect I sound MAINLY the ability to remember, and of course the rest being an actual ability to Understand that subject matter.

    Anyway I do drink probably a little too much at the moment(2 x very strong, plus a small instant coffee per day), but I do love it. I just love being more alert, and I cannot stand feeling tired (oh, by the way I haven’t touched any illicit drugs for 7 years now).
    What I have found is that although you do build an immunity/tolerance to the caffeine/coffee, it seems to level out at a certain point, whereby I have not continually increased more and more over the years, as you would do if you were using heroin/meth etc - with those you just keep using more all the time, at least for everyone I ever knew who did, which were hundreds of different users…indeed, we all did.
    So that being said I have found myself to drink no more than a two super strong coffees a day(3 or more shots in each) AND IMPORTANTLY, and this is what i try and tell people who drink 5-10cups a day, you only need a couple of strong hits to last you, otherwise I, like i see most of them do, drink copious amounts of normal to moderate strength cups(1-2 shots max) all day long, never really "feeling" much stimulatory affects at all during the day, OR never feeling them for very long either – which I absolutely believe enables those who “fall straight to sleep after a coffee” to do – the reason? It’s a week coffee – seriously let me make them one of my normal coffees – I guarantee they will not be sleeping…
    Yes of course coffee tastes nice, but the reality is, if i could give you an exactly the same-tasting decaf cup of coffee, you would not drink it - and the reality is, people don’t, they have the caffeine one that has an effect on them, even if it is a small effect…..absolute proof to the people who profess they drink only for the "taste" - yeah whatever...(now I know some of you may, but you are the absolute tiny minority, the rest drink for taste AND caffeine effect.
    Just my opinions and perceptions…

    Sorry last bit of fourth paragraph above should read "and loosely – in effect I sound STUPID, and I believe that “intelligence” seems to be MAINLY the ability to remember, and recall facts, but, and of course the rest being an actual ability to Understand that subject matter."

    You could tell John was wired when he wrote this lol

    to each one here claiming his/her perception of coffee is the correct one (for example, john who says "those who say "it doesn't effect me" are delusional") need to go back and re-read the introductory paragraphs. paying special attention to the phrase "it works differently on different people with different tolerances — even in different menstrual cycles"...your experience with coffee is your individual experience, don't tell me what mine is or should be.

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