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How does long-term use of caffeine affect productivity?

12 Post author: quartz 11 April 2012 11:09PM

I am trying to figure out whether caffeine helps productivity in the long run. Looking back 10 years from now, how much more/less productive will I have been if I were to drink coffee every day, or every second day?

Reviewing what has been written on the topic by our community so far:

  • Justin summarizes effects of caffeine: impairment of long-term memory, narrowed focus, increased short-term memory and recall, increased attentional control, increased memory retention and retrieval. From this, he tentatively concludes in favor of use for tasks that benefit from these effects. However, does this conclusion still hold for regular use? We need to take into account reduced stimulation due to increase in tolerance and potentially impairment during withdrawal.
  • In a comment on Justin's article, simplyeric writes: "There are studies (that I read years ago, and have no link to) that show that consistency is better... that consistent low-level caffeine drinkers are more alert than their non-caffeine colleagues, but less jittery than high-caffeine people (optimum seemed to be 2-3 cups per day)." This is the kind of evidence I am interested in. Does anyone recall such studies?
  • Gwern's review of nootropics lists a number of potential negative effects, including effects on memory, performance (in high doses), sleep, and mood. In justifying its use despite these effects, he states that "[his] problems tend to be more about akrasia and energy and not getting things done, so even if a stimulant comes with a little cost to long-term memory, it's still useful for [him]". Is there conclusive evidence that in the long run, caffeine increases energy and helps with akrasia?
  • Skatche's review of psychoactive drugs presents anecdotal evidence in favor: "Taken on a fairly regular daily schedule, caffeine seems to improve my attention, motivation and energy level." To what extent do such anecdotes reflect true improvement? If regular use of caffeine were to result in decreased baseline performance and if the effect of caffeine were limited to restoring baseline, this could feel similar from the inside.
Edit: Studies pointed out by siodine suggest that caffeine has few or no beneficial long-term effects:
If caffeine was consumed, the adverse effects of lowered alertness and headache were avoided, but even after 100+150 mg of caffeine their alertness was not raised above the level of alertness showed by nonconsumers of caffeine (group N) who received placebo (Figure 1, middle panel). This result is similar to that from an early study comparing responses to caffeine of coffee drinkers and abstainers (Goldstein et al, 1969), and is consistent with the claim, supported by a variety of subsequent findings, that regular caffeine consumption provides little or no net benefit for alertness or performance on tests of vigilance (James and Rogers, 2005; Sigmon et al, 2009).
The study also demonstrated robust acute effects of caffeine unconfounded by caffeine withdrawal, but no evidence for net beneficial effects of daily caffeine administration.
Overall, there is little evidence of caffeine having beneficial effects on performance or mood under conditions of long-term caffeine use vs abstinence. Although modest acute effects may occur following initial use, tolerance to these effects appears to develop in the context of habitual use of the drug.

Comments (28)

Comment author: gwern 11 April 2012 11:56:11PM *  7 points [-]

I am trying to figure out whether caffeine helps productivity in the long run. Looking back 10 years from now, how much more/less productive will I have been if I were to drink coffee every day, or every second day?

While you're looking for studies, have you considered just starting a double-blind experiment? If you've read my page on nootropics, it should be pretty clear how you could do it with a water-soluble substance like caffeine and where you could get cheap bulk caffeine.

Comment author: bcoburn 12 April 2012 12:17:18AM 4 points [-]

Just for the record, and in case it's important in experiment planning, caffeine isn't actually tasteless at all. has a fairly bitter and certainly easy to recognize taste dissolved in just water.

It is, however, really easy to mask in, for example, orange juice, so the taste shouldn't make the experiments hard as such. Just another design constraint to be aware of.

I'd also recommend adding some sort of n days on, m days off cycling to your tests, mostly because that's what I do and I want to take advantage of other people's research.

Comment author: gwern 12 April 2012 12:24:18AM 1 point [-]

I'd also recommend adding some sort of n days on, m days off cycling to your tests

There's a lot of possible schedules; you need to start somewhere.

Comment author: wedrifid 12 April 2012 07:03:01AM 4 points [-]

Just for the record, and in case it's important in experiment planning, caffeine isn't actually tasteless at all. has a fairly bitter and certainly easy to recognize taste dissolved in just water.

Sounds like it is time for cheap gelatin capsules.

Comment author: thelittledoctor 12 April 2012 05:48:39AM 5 points [-]

You wouldn't likely be able to just dissolve anhydrous caffeine powder in water and keep yourself blinded; it's incredibly bitter (second only, in my experience, to tongkat ali / eurycoma longifolia root powder).

Comment author: bogdanb 14 April 2012 11:22:08AM 0 points [-]

You just need a similarly bitter placebo. Make (sugar+caffeine) and (sugar+quinine)* such that you can’t tell the difference and ask a friend put to them in two bottles labeled with “A” and “B”.

(*: Quinine is probably a bad choice for a placebo, since it has its own effects that might confuse the results. It’s just the first thing that came to mind that’s bitter.)

Comment author: wedrifid 12 April 2012 07:05:42AM 3 points [-]

While you're looking for studies, have you considered just starting a double-blind experiment? If you've read my page on nootropics, it should be pretty clear how you could do it with a water-soluble substance like caffeine and where you could get cheap bulk caffeine.

If you are doing it just on yourself isn't it just a blind experiment?

Comment author: gwern 12 April 2012 03:35:17PM 2 points [-]

It's useful to say 'double-blind' rather than 'blind' to forestall confusion - 'double-blind' caters both to people clever enough to realize that blind=double-blind for self-experimenting and also to people not that clever or just not thinking of it.

Comment author: wedrifid 12 April 2012 03:49:06PM *  3 points [-]

It's useful to say 'double-blind' rather than 'blind' to forestall confusion - 'double-blind' caters both to people clever enough to realize that blind=double-blind for self-experimenting and also to people not that clever or just not thinking of it.

Yeah, I tend to be conflicted when describing such experiments, for that reason. To most 'double-blind' just sounds like a word for 'scientific' and writing "blind (which incorporates all the rigor inherent in 'double-blind' in as much as both the subject and the experimenter are blind but it isn't "double blind" per se since it is just one dude" is a little verbose. I think I may just go with "self-blinded experiments".

Comment author: thomblake 12 April 2012 04:45:08PM 3 points [-]

In skeptical circles, saying "double-blind" for self-experimentation is a watchword for crankdom. It often gets followed by something like "Can you describe the procedure you followed to make the experiment double-blind?"

Comment author: gwern 12 April 2012 05:18:13PM 2 points [-]

It is?

Comment author: thomblake 12 April 2012 06:05:17PM 1 point [-]

I can't find a reference quickly - apparently it's not as common as I'd thought.

Comment author: DanielLC 12 March 2015 05:18:10PM 0 points [-]

Double-blind means that neither the scientist nor the subject know which is the control. Blind would be just the scientist knows. If you do an experiment on yourself, it can't be just a blind experiment.

Comment author: Hicquodiam 12 April 2012 02:05:44AM 1 point [-]

When I drank coffee for about a year, I didn't have any noticeable impairments, at least nothing that slapped me in the face.

The withdraws though... oh god the withdrawals.

Comment author: fiddlemath 12 April 2012 05:17:55AM 4 points [-]

My withdrawals are a couple of lazy days, with a nasty headache about 24 to 30 hours after the last cup. Are yours much worse than this?

Comment author: Hicquodiam 12 April 2012 05:35:53AM 1 point [-]

Haha nah, I'm just overdramatizing the headaches I got - I'm a little baby. They did make me slip back a few times though.

After I cut out the coffee, I had probably about two days of withdraws, then stopped noticing anything.

Comment author: advancedatheist 12 April 2012 02:48:08PM 3 points [-]

Your genome may have something to do with caffeine's long-term effectis. According to 23andMe, I have a variant of the marker rs762551 which supposedly makes me a "fast caffeine metabolizer." Apparently the alleles for slow caffeine metabolism can increase your heart attack risk from drinking coffee.

Reference:

Coffee, CYP1A2 genotype, and risk of myocardial infarction.

http://www.ncbi.nlm.nih.gov/sites/entrez?cmd=Search&db=pubmed&term=16522833

Comment author: quartz 12 April 2012 08:17:37PM 2 points [-]

Am I the only one who finds it astonishing that there isn't widely known evidence that a psychoactive substance used on a daily basis by about 90% of North American adults (and probably by a majority of LWers) is beneficial if used in this way? What explains this apparent lack of interest? Discounting (caffeine clearly has short-term benefits) and the belief that, even in the unlikely case that caffeine harms productivity in the long run, the harm is likely to be small?

Comment author: gwern 12 April 2012 10:49:21PM *  6 points [-]

Caffeine is extremely cheap, addictive, has minimal effects on health (and may be beneficial, from the various epidemiological associations with tea/coffee & longevity), and costs extra to remove from drinks popular regardless of their caffeine content (coffee and tea again). What would be the point of carefully investigating it?

Suppose there was conclusive evidence on the topic, the value of this evidence to me would be roughly $0 or since ignorance is bliss, negative money - because unless the negative effects were drastic (which current studies rule out), I would not change anything about my life. Why?

I enjoy my tea too much. My usual tea seller doesn't even have decaffeinated oolong in general, much less various varieties I might want to drink, apparently because de-caffeinating is so expensive it's not worthwhile. What am I supposed to do, give up my tea and caffeine just to save on the cost of caffeine? Buy de-caffeinating machines (which I couldn't even find any prices for, googling)? This also holds true for people who drink coffee or caffeinated soda.

(As opposed to a drug like modafinil which is expensive, and so the value of a definitive answer is substantial and would justify some more extensive calculating of cost-benefit.)

Comment author: jsalvatier 19 April 2012 05:54:58PM 3 points [-]

I, for one, would start drinking coffee regularly if there were proven benefits to doing so.

Comment author: siodine 12 April 2012 08:48:19PM *  7 points [-]
Comment author: quartz 12 April 2012 08:55:30PM *  4 points [-]

Nice! This is exactly the kind of evidence I'm looking for. The papers cited in the intro also look highly relevant (James and Rogers, 2005; Sigmon et al, 2009).

Comment author: shokwave 13 April 2012 08:52:38AM 0 points [-]

As far as I'm aware there are no long-term effects of caffeine that are positive for productivity, unless you count repeatable short-term effects aggregating over a long time period as a 'long-term effect'.

Comment author: gwern 13 April 2012 04:37:48PM 1 point [-]

I think this discussion could benefit from distinguishing between long-term/short-term and acute/chronic.

Comment author: Eneasz 13 April 2012 08:30:49PM *  0 points [-]

I basically gave up on caffeine almost a year ago. I've not noticed any overall changes, aside from not having an addiction. There is one short-term benefit that regular users seem not to have - if I've had a very late night or for some other reason I'm very tired but I need to keep going, I can take some caffeine and run normal(ish) for several hours. It's saved me a few times, I'd be disappointed to lose that tool.

I do miss the taste of coffee though.

Comment author: scaphandre 14 April 2012 05:30:00PM 1 point [-]

I'm aware that my caffeine use might have little benefit to total productivity over the course of a week.

I do attach value to using caffeine to choose to be less susceptible to tiredness for the next few hours.

Does that make sense?

Comment author: Duncan 16 April 2012 05:05:23PM 0 points [-]

Long term caffeine tolerance can be problematic. To combat this problem, every 2-4 months I stop taking caffeine for about 2 weeks (carefully planned for less hectic weeks). In my experience and that of at least one other colleague this method significantly lowers and possibly removes the caffeine tolerance. Two people does not make a study, but if you need to combat caffeine tolerance it may be worth a try.

Comment author: Swimmer963 27 October 2014 10:22:21AM 0 points [-]

Anecdotally, it doesn't feel like I get overall improved functioning from caffeine, but I can use it to gain control of when my high-alertness and low-alertness periods will happen. This is 100% a must for the kind of shift work schedule I'm doing right now, which definitely was not intended for humans. I usually consume caffeine at work only and minimize it on my days off; ideally this adds up to consuming it on 4/9 days, in practice more because I take overtime. I take longer breaks whenever possible. Caffeine is pretty much what allows me to function during 12 hour night shifts.

I think that maybe if I could completely remove the effects of current caffeine dependence, I might be able to handle 12 hour day shifts (7 am-7 pm) caffeine free, but I'm not sure about that. Caffeine helps smooth out dips and slumps in my circadian rhythms, and I need all of the alertness I can muster to take care of humans on ventilators.