“This little fruit is the source of happiness and wit!” – Dr. William Harvey, discoverer of blood circulation, speaking of the coffee bean as he lay on his deathbed in 1657
In my mid-20s I was an aspiring coffee snob, and I ground artisan roasts for my cheap little espresso machine. Later, I had a green tea obsession, particularly matcha. I became preoccupied with optimizing frequency, quality, and brew strength. At the apex (or nadir) of this period, I tried using No-Doz™ cut into quarter pills (50mg) for more precise and continuous dosing. I put a little dish of them by my bed, and upon waking up in the morning, I would eat one; I chewed it so it would take effect faster, and I found the bitter taste bracing. (It confused me to find that friends and family were creeped out by my use of caffeine pills, when for some reason they’d had no problem with coffee, tea, or soda.) Through these phases, I would get migraine headaches every week or so, and mood swings somewhat more often, and I could never tell for sure when I actually needed sleep vs. when I needed more caffeine.
It finally occurred to me that if you average out the effects of habitual daily caffeine use, caffeine is actually a depressant. Wikipedia’s article on caffeine dependence informs us that caffeine works by blocking the action of the neurotransmitter adenosine on its receptors. Since adenosine receptors generate a feeling of tiredness when they are activated, caffeine intake prevents this and creates alertness—initially. But in a matter of days, the body builds tolerance by adding more adenosine receptors. Increased adenosine receptors means that even though the body may continue to produce the same amount of adenosine, the effect of any adenosine in the system is multiplied. So after developing dependence on caffeine, the baseline state of wakefulness is lowered, and caffeine intake becomes required just to restore normal wakefulness again. In order to feel a “buzz,” you need to consume more caffeine than it takes to restore normal wakefulness, and if you do this for more than a few days, the body adapts again by growing more adenosine receptors which further dampens steady state.
Yes, but what about all of those performance enhancing effects of caffeine? The media sometimes reports that scientists have been measuring benefits of caffeine for attention, mood, reaction time, and athletic performance in a variety of studies. Apparently, though, many of these studies used caffeine-habituated populations, so the supposed benefits appear to be just withdrawal relief.
It is clear that to a certain extent, after habituation, caffeine use doesn’t boost your performance so much as give you back your performance which it has taken away. So the question is: are there benefits to caffeine use despite this or compensating for this? More than 85% of the adults in the United States use caffeine regularly, so all of those people must believe the answer is yes. But is it the case, or could they all just be addicted to something that is not providing value?
This question is hard to test. I was never disciplined or patient enough to try to quantify my attention and performance with and without caffeine and under both habituated and nonhabituated conditions. But over many years, I cycled between states of regular use and abstinence, and I made some observations. I had my turn acting out the archetypal image of the coffee drinker before their first morning cup, grumpy and unfocused. I also, during abstention periods, bounced out of bed fully alert and lucid after a good night’s sleep.
What gave me the resolve to quit for good was when the “selfish gene” angle occurred to me. A supposedly performance-boosting substance doesn’t have to actually boost your performance to get you to continue using it. All it has to do is make you think it’s boosting your performance. Even when you’re buzzed, feeling revved up and productive, it’s possible that you’re not actually productive. You might just feel productive, while you’re turning useless cranks. If the substance is targeting your feeling of productivity, you may not be able to tell the difference, right? When I thought back over my use of caffeine, I realized this was not far from the truth in my memory. Being juiced on caffeine has consistently harmed my lateral thinking and big picture context awareness (such as it is). So, subjecting myself to dependence and withdrawal cycles for the sake of a couple of hours of feeling-productive-but-not-really, which is not sustainable anyway due to habituation, seemed like something it was clearly a good idea to avoid from then on.
To be fair: caffeine doesn’t seem to be harmful to health. In fact, some studies suggest it is protective against Parkinson’s. So if you accept that caffeine doesn’t actually make you more alert, you might tolerate an obligation to stave off withdrawal for the sake of health benefits. But chronic caffeine use has some other negative effects which may not completely attenuate with habituation. For example, caffeine use raises levels of cortisol, the “stress hormone,” so there’s an argument that caffeine use impairs emotional intelligence, because constant exposure to fight-or-flight conditions may be an impediment to empathy and otherwise playing nice with others.
Apart from the caffeine, coffee and tea furnish health-promoting substances called polyphenols. But processes to decaffeinate coffee and tea are only somewhat effective, and they inflict collateral damage on the quality of the beverage. Fortunately, there are herbal sources of polyphenols, such as hibiscus and rooibos.
I still keep caffeine in the toolbox, since it is available basically everywhere. I’ll occasionally have some caffeine if I will be in a series of meetings and didn’t get enough sleep the night before, or I’ll have a cup of tea just for pleasure on a social occasion. But I am careful not to do this more than one or two days in a row, otherwise the hooks start to set in. I also try, if I’m going to have a caffeinated beverage, to have it as early in the day as possible, since the half-life of six hours means that it seems to take at least 12 hours for the effect to wear off enough for me to sleep.
But as for the 85% of the population that caffeinates themselves habitually, I am determined not to judge. Given the lack of any known health hazards, I am definitely not in a position to say that the texture and pleasure of a coffee or tea ritual isn’t worth it.
References for the 1657 William Harvey quote:
The 2002 study “Effects of caffeine on performance and mood depend on the level of caffeine abstinence” (PubMed) found that after neutralizing caffeine withdrawal, there were no additional benefits on alertness or mood. The rationale for the study reports, “Most studies of the effects of caffeine on performance have used regular caffeine consumers who are deprived at test.” ↩
Source for the 85% statistic: Anderson BL, Juliano LM, Schulkin J. Caffeine’s implications for women’s health and survey of obstetrician-gynecologists’ caffeine knowledge and assessment practices. J Womens Health (Larchmt) 2009;18:1457. PubMed ↩
Here’s a study which found that elevated cortisol levels were not completely eliminated with habituation, and an article which presents the hypothesis that caffeine is the “silent killer of success” via sabotaging emotional intelligence. ↩