Is caffeine a cognitive enhancer?



I don’t drink coffee. I never have.

Late in my PhD, I did have a rather unhealthy addiction to energy drinks, but I managed to knock that on the head once I had submitted.

As a non-coffee drinker, I watch with fascination the critical role coffee plays in many people’s lives.

People start their day with coffee, they turn to coffee when they need to concentrate, and they rely on coffee to get them through periods of hard or late work. Caffeine is the most frequently consumed psychostimulant and second most popular beverage (after water).

Many people I talk to also describe themselves as ‘addicted’ to coffee, and experience unpleasant side effects (headaches, fatigue) and cravings if they attempt to reduce their intake. Consistent with this, the evidence does suggest you can build up a tolerance to caffeine, particularly in the central nervous system (i.e. the mental effects).

Whilst taste might be the central motivator for some drinkers, I suspect it is the psychological and physical effects of caffeine that keep most people drinking it on a regular basis.

In particular, it seems to be the ‘lift’ that caffeine gives people when they are feeling tired or unmotivated that is important. Caffeine seems to have a cognitive enhancing effect, where it (at least temporarily) improves energy, concentration, focus and maybe even learning and memory ability.

This got me thinking.

Am I missing out on an effective cognitive enhancer by not drinking coffee? Is caffeine really a good cognitive enhancer?

Thankfully I am not the only person to have asked that question, so turning to the literature yielded a number of papers on the topic (1, 2, 3)


What caffeine does seem to do

Caffeine is not just found in coffee. It can be found in coffee, tea, guarana, chocolate, and soft drinks. This means it is actually very hard to find people that aren’t consuming some caffeine in some way.

This poses a big challenge for researchers in the area, because it is hard to find a suitable ‘caffeine-free control group’ to compare against. Mostly studies are done with participants who are required to abstain from caffeine use prior to the research. Unfortunately this creates a bit of a challenge where researchers cannot be sure that the caffeine is actually providing genuine benefit, or whether it is simply providing relief from withdrawal; returning participants to their prior level of caffeine consuming functioning.

It can also be difficult to separate out the effects of caffeine from the effects of other substances that are commonly packaged with caffeine, particularly sugar and other stimulants like guarana.

These difficulties aside, my reading of recent reviews suggest that caffeine itself does genuinely provide the following benefits:

Coffee yes

1. Caffeine helps people stay awake and alert. In low (~1 cup black tea) and moderate doses (a couple of cups of strong coffee), caffeine improves concentration, vigilance and reaction time, even in habitual users (although the acute effect gets smaller, the more regularly you consume). Caffeine can help sustain attention during demanding tasks (that last minute assignment) and can counteract the decline in performance from morning to afternoon (that is why all my colleagues fire up an afternoon coffee!).

The evidence is clear that caffeine can maintain performance in fatigued individuals. For example, think about all those professions where fatigue is likely because of restricted or irregular sleep (e.g. military, first responders, transport workers and factory shift workers). Repeated caffeine doses can help maintain physical and cognitive capabilities in these individuals and reduce failures and accidents at work. I’d suggest that many students, because of the challenges of juggling work, family and study, have disrupted sleep and use caffeine to preserve their abilities.

Keep in mind though that this is simply a preservation of abilities (not a boost) and should really only be used under circumstances of unavoidable fatigue. Also, there is the suggestion that caffeine use in situations of reduced alertness really only preserves simple or very well rehearsed functions. So expecting caffeine to restore your full ability to think, reason and problem-solve during periods of fatigue is unrealistic.


2. Caffeine improves sports performance. Maybe not your primary goal as a student but according to this paper – “Effects on physical performance on a vast array of physical performance metrics such as time-to-exhaustion, time-trial, muscle strength and endurance, and high-intensity sprints typical of team sports are evident following doses that exceed about 200 mg”. Supposedly a moderate dose about an hour before training/competition increases performance. Want more information about this – try the Sports Dietitians Australia website.


3. Caffeine can cause anxiety and agitation with high doses. So this is an interesting one. At low and moderate doses, caffeine leads to an increased ability to experience pleasure and lower anxiety (sounds nice), but at higher doses tends to produce tense arousal/ anxiety/ nervousness/ jitteriness. However what constitutes a ‘high’ dose will vary by individual. For example, one of the reasons I think I have never taken to coffee is that even small doses of caffeine usually make me feel agitated and unwell. Certainly amongst my friends and colleagues that drink coffee, almost all have described reaching a point where that had a ‘bit too much’ and started feeling unwell.


4. Caffeine can improve learning and memory, sorta. Along with concentration and alertness, I’m guessing this is probably the effect that most students are hoping caffeine will have. From what I can gather “caffeine facilitates learning in tasks in which information is presented passively“. So that coffee you have before attending your lectures probably will help you focus and remember some more of what you are told.

The evidence that caffeine improves memory and learning directly though is a bit sparse and contradictory. It appears that any learning or memory improvements associated with caffeine intake are primarily due to caffeine making you more alert and awake. You remember the material better cause you are more alert when you learn it.  So improvements in memory and learning from caffeine intake are most notable when you are tired, when the content is a bit boring and you lack interest or for older people whose overall energy levels might be lower.

I did however find an article that suggested caffeine intake following study can enhance the consolidation of long-term memories, so the exact effects of coffee on learning and memory are still an area of active research.

5. Caffeine may be protective against neurodegenerative diseases like Alzheimers. There is increasing evidence that moderate caffeine intake (e.g. a couple of coffees a day) may be protective against diseases like Alzheimer’s and Parkinson’s disease. If you’ve just arrived at university from high school, these disorders might not be particularly high on your priority list, but it is always a little comforting when a much enjoyed daily habit turns out to have health benefits (my enjoyed daily habit of eating crisps is not associated with any health benefits – bugger).


6. Caffeine can help analgese headaches. Whilst caffeine withdrawal can cause headaches, caffeine itself can improve headaches, especially when combined with popular pain relievers like aspirin, paracetamol and ibuprofen.  Caffeine narrows the blood vessels that feed the brain – supposedly that is the mechanism of action. However, because the withdrawal from caffeine can increase headaches, those who experience them regularly (including migraines) are sometimes recommended to abstain from too much caffeine.


7. Caffeine can improve your mood. Supposedly a coffee every 4 hours can sustain a measurable improvement in mood. In lower doses, caffeine induces a sense of calmness and interest. Increased intake is associated with a lower risk of depression. It seems that outside of having a few too many (leading to anxiety, nervousness), moderate coffee consumption is, on average, beneficial for mood. As with the findings for alertness/learning/memory, it might be that positive mood impacts are more noticeable in individuals whose baseline level of arousal (due to age, or fatigue) is lower.


Coffee No

What caffeine can’t really do (at least as far as we know)

1. Caffeine can’t make you smarter. It can make you more alert, improve your concentration, it can help you process information a little more quickly (particularly if fatigued), but it doesn’t actually make you process information in a different way. It doesn’t help with ‘higher order executive functioning” – i.e judgements, decision making, problem-solving.

2. Caffeine can’t sustain or improve performance in high performance situations. Caffeine can help you in passive or low complexity situations. But turn up the heat in terms of the complexity of the task, and caffeine is not really going to help you much. Have a complex essay to write? Caffeine will help you stay awake, but not make you any better at essay writing.

3. Caffeine can’t fix ADHD. Individuals with ADHD are commonly given stimulant medications (yes, it does seem a bit contradictory, but it works). As caffeine is a stimulant, it does provide some benefit to individuals with ADHD, but in no way better than prescribed medications.

4. Caffeine is less helpful to regular consumers of it. If you already consume a significant amount of caffeine, you will unlikely get much benefit from additional amounts. You are more likely to experience the effects of mild overdose (anxiety, jitters, etc). In fact, you are more likely to experience performance decrements  if your caffeine intake falls.

5. Caffeine can’t make time travel possible. Hopefully this is just self-evident.


Takeaway message

My reading of an admittedly small number of review articles suggests there are positive reasons to be a regular consumer of caffeine (within guidelines). This is particularly the case if you have unavoidable fatigue or tiredness arising from insufficient or irregular sleep patterns.

For increasing alertness, concentration and focus, mood and learning caffeine seems to be an effective and safe method. It isn’t a miracle substance though. Most of its effects are achieved through a general increase in arousal level, not an increase in intelligence or ability to work with and process information. If you write crappy essays without caffeine, you’ll probably write crappy essays with caffeine (maybe a little faster).

The positive impacts of caffeine intake on preserving abilities during periods of high fatigue should be treated cautiously. Caffeine is not an excuse to maintain or even celebrate poor lifestyle habits (e.g. sleep). Whilst late nights and busyness are often unavoidable, When such , as the cognitive enhancing properties of good quality, regular sleep are well documented also. Certainly not an excuse

If you are a regular consumer of caffeine and there aren’t other reasons for you to modify your intake (save money, reduce calories etc), the evidence to date would not suggest changing your behaviour. If anything there is likely to be net benefits for you. Keep in mind the source of your caffeine is important here. If you are getting all your caffeine through sugar-laden beverages, then you are potentially facing other risks, that outweigh any performance benefits (e.g. diabetes).

If you aren’t a regular consumer, take comfort in the fact that the reported benefits aren’t anything that couldn’t be achieved through some simpler and maybe cheaper alternatives (regular sleep, good quality diet, physical activity).

So, in answer to the question posed in the title of this post – ‘Is caffeine a cognitive enhancer?’

The answer is ‘kinda’.

Caffeine is not a pure cognitive enhancer in that it does not appear to make us smarter. It helps via its effects on arousal, mood and concentration.

Think of it like this. That morning coffee will help you pay attention in the lecture, but probably not make you any more likely to understand it.


Wanna read more?

Try this if interested primarily in caffeine, or try this article if you are interested more broadly in the topic of cognitive enhancement.

This post from the British Psychological Society covers a few psychological outcomes not addressed in this article.

Remember, where possible, to focus on articles discussing the peer reviewed literature, rather than random websites or blogs, as there is lots of bad advice floating around about cognitive enhancement.


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