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).
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.
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).
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.)
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.
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.
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.
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?
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.
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?"
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".
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.
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?
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.)
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
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.
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.
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?
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.
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'.
I think this discussion could benefit from distinguishing between long-term/short-term and acute/chronic.
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.
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?
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.
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:
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.