TL;DR · Executive summary
- Caffeine does not give you energy – it only temporarily blocks the feeling of tiredness (by occupying adenosine receptors). The fatigue does not disappear; we simply stop feeling it.
- It improves short-term alertness and attention, but not creativity, memory, or the ability to see the bigger picture.
- It impairs sleep – shorter and shallower, even many hours after consumption. This creates a cycle: poor sleep → coffee → even worse sleep.
- It causes physical dependence: withdrawal symptoms (headache, fatigue, irritability) appear with as little as one coffee a day. The morning cup often just suppresses withdrawal, not 'recharges.'
- The health "benefits" from newspaper headlines come from observational studies and have not been proven to be causal.
- The point: it's not about quitting coffee, but about stopping it at least once for long enough to discover your true, natural state.
That sentence resonated with me all the more because I had recently watched a documentary about how deeply coffee is embedded in our culture. Coffee machines in offices. Paper cups in the hands of movie characters. Starbucks. “Let’s grab a coffee” as a synonym for meeting up. The morning coffee as an almost mandatory part of adult life.
I do have a coffee myself occasionally. I like the bitterness. The aroma. The ritual.
At the same time, I noticed that it made me more anxious, worsened my sleep, and upset my digestion.
So I started asking: is this just my impression, or can coffee really do some of the things I attribute to it?
The deeper I dug into the topic, the more I became interested in a different question altogether.
What if the morning coffee – widely regarded in our culture as the solution to our tiredness – is actually its main cause?
Coffee Does Not Give Us Energy. It Changes How We Feel Tiredness.
When we have quality protein with vegetables for lunch, we supply our body with energy and building blocks. Nutrition. When we sleep, we allow it to recover.
Caffeine works differently.
Throughout the day, the activity of a substance called adenosine gradually increases in the brain. Put very simply, it is part of the system the brain uses to register how long we have been awake and how much we need sleep.
Caffeine binds to the adenosine receptors and temporarily blocks its signal.
As a result, we do not feel tiredness as intensely.
But the biological need for rest has not disappeared.
It is a bit like taping over the low-fuel warning light in a car. The light stops alerting us and we drive on. But we are still running on fumes.
This does not mean caffeine “does nothing”. It is a potent psychoactive substance. It can demonstrably improve short-term alertness, attention, and reaction times.
The question is rather: Is this performance free of charge?
The Brain on Coffee: Better Thinking, or Mainly More Arousal?
Here we should give coffee the credit it deserves.
Caffeine can acutely improve alertness, attention, and reaction time. This is well established experimentally.
So if I need to narrowly focus my attention for two hours – working with a spreadsheet, driving, or programming – caffeine can objectively help.
But alertness is not the same as higher-quality thinking.
According to studies, coffee does not help with creative thinking, perceiving connections, or memory.
In my view, the question that suggests itself is whether caffeine, while helping us focus on a specific problem, might at the same time at least partially block the perception and linking of broader contexts. However, I found no evidence for this.
One of the things that shocked me the most concerns blood flow to the brain after coffee.
Caffeine can acutely and quite significantly reduce cerebral blood flow. In experimental studies, the reduction reaches as much as 20–40 % lower blood flow to the brain after coffee consumption.
It should be noted that lower blood flow does not automatically mean the brain receives proportionally less oxygen. The brain can extract a greater share of oxygen from incoming blood, and its total consumption may, according to current knowledge, remain roughly preserved.
It is nevertheless remarkable that a substance we barely think twice about consuming can so dramatically alter brain physiology.
The Bill We Pay in the Morning
One of the areas best researched when it comes to coffee is its effect on sleep.
A systematic review and meta-analysis of 24 studies from 2023 found that caffeine on average:
- shortened total sleep by about 45 minutes,
- reduced sleep efficiency by about 7 percentage points,
- prolonged the time to fall asleep by 9 minutes,
- increased night-time wakefulness by 12 minutes,
- and reduced deep sleep by 11 minutes.
At the same time, evidence suggests that caffeine affects sleep quality even when we do not subjectively feel it.
That is why the statement:
“I can have an espresso and be asleep in ten minutes.”
is not proof that caffeine does not objectively impair our sleep.
It turns out that without that coffee, sleep would likely be longer and of higher quality – and we would be better rested the next day.
There is even a study in which a morning coffee at 7:00 negatively affected sleep at 23:00 – that is, 16 hours after consumption (!).
And this is precisely where a potentially unpleasant cycle emerges:
poor sleep → caffeine → less perceived tiredness → worse subsequent sleep → greater tiredness → more caffeine
If I regularly wake up without energy in the morning and need my morning cup as soon as possible to get on my feet, it is worth asking:
Is the problem really a lack of caffeine?
The Addiction Nobody Talks About
“Smoking causes addiction” is a sentence found on every cigarette packet.
Have you noticed anything similar on a Starbucks cup?
I do not mean to compare the harmfulness of coffee and cigarettes.
But one thing we do know:
caffeine causes physical dependence.
With regular use, the body adapts. Part of the effect gradually fades – tolerance develops.
And like every substance that causes dependence, withdrawal symptoms appear when caffeine is discontinued.
A large critical review of 57 experimental and 9 survey studies confirmed, among others:
- headache,
- fatigue,
- drowsiness,
- decreased energy,
- reduced alertness,
- difficulty concentrating,
- brain fog,
- irritability,
- lowered mood.
Symptoms typically begin 12–24 hours after stopping, peak at roughly 20–51 hours, and usually last 2–9 days.
And perhaps most surprisingly:
Withdrawal symptoms have been experimentally observed with a regular intake of as little as around 100 mg of caffeine per day.
That is roughly one ordinary coffee.
In experimental studies, about half of people experienced a headache after stopping, and approximately 13 % had symptoms severe enough to noticeably impair their functioning.
The typical withdrawal headache ties neatly to what we already mentioned:
Caffeine constricts brain blood vessels. With regular use, the body adapts. When caffeine is suddenly removed, the vessels dilate and blood flow increases. And that is precisely why going “without coffee” can give us a headache.
Energy or Anxiety? Sometimes the Line Between Them Is Thin.
Caffeine increases the activation of the central nervous system.
In one person, this state can subjectively mean:
- energy,
- concentration,
- motivation.
At higher intensity, however, the very same stimulation can mean:
- nervousness,
- inner restlessness,
- heart pounding,
- muscle tension,
- irritability,
- anxiety.
And this effect is not merely a subjective impression.
In controlled experiments, anxiety increases with the dose of caffeine. The effect is most pronounced in people predisposed to panic attacks and other psychological issues.
According to one meta-analysis, after high doses of caffeine (roughly 5–8 ordinary coffees), approximately half of patients with panic disorder experienced a panic attack, while among healthy controls the figure was less than 2 %.
So my own nervousness after coffee was probably not just autosuggestion.
Is the Morning “Boost” Even Real?
“Without coffee in the morning I’m not a person.”
We usually interpret this sentence as proof of how wonderfully coffee works.
But when we factor in the addictiveness, the effects on the brain, and withdrawal symptoms, it appears that for regular coffee drinkers the morning cup may be suppressing withdrawal symptoms rather than genuinely boosting morning energy.
If I do not drink caffeine regularly, my situation might look roughly like this:
normal state → coffee → stimulation
If I drink coffee every day, the morning may look more like this:
onset of withdrawal → fatigue, poorer attention, headache → coffee → withdrawal relieved → “I can finally function”
And that leads to an interesting question:
What would my natural state look like after three weeks without caffeine, once the withdrawal symptoms are long gone?
Would I sleep better? Feel calmer? Have more stable energy? Or would I objectively miss caffeine?
And What About the Health Benefits of Coffee?
You may have come across a headline along the lines of “Three to four coffees a day are linked to a longer life” – more precisely, that moderate coffee consumption (3–4 cups a day) is associated with several health benefits, for example:
- lower overall mortality,
- lower risk of cardiovascular disease,
- lower risk of type 2 diabetes,
- lower risk of Parkinson’s disease,
- lower risk of certain liver diseases.
The problem is the word linked.
A large share of this data comes from observational studies. We follow hundreds of thousands of people and notice that those who drink a certain number of coffees have somewhat lower mortality.
That is relevant information.
But it is not proof that the difference was caused by coffee.
People who do and do not drink coffee may differ in dozens of other ways: smoking, diet, health status, physical activity, socioeconomic status, or the reason why someone stopped drinking coffee.
Interestingly, when a different approach is used – a genetic method called Mendelian randomisation – the observed protective effect of coffee on cardiovascular disease and overall mortality is not confirmed.
This does not mean coffee has no health benefits.
It only means that grand claims like “Coffee extends your life” have not been proven as causally as we can experimentally demonstrate, for example, its effect on sleep or withdrawal symptoms.
“Don’t Take Away Our Coffee!”
This piece is not meant to be a manifesto against coffee. I enjoy the occasional cup myself and have no intention of turning it into an enemy.
What struck me while writing, though, is how strange it is that we barely think about it at all. Every day we alter the chemistry of our brain with a substance that suppresses the (natural) feeling of tiredness, affects sleep, and with regular use creates physical dependence – and yet we perceive it almost as neutrally as a glass of water.
Maybe coffee is a great tool for some people. Maybe it genuinely helps someone function better.
But maybe there are also people who have been using their morning coffee for years to treat tiredness to which their daily caffeine routine at least partly contributes.
And they will never find out, because they never stop caffeine for long enough.
What if, after two or three weeks without caffeine, we discovered that we sleep better, feel calmer, and have more natural energy throughout the day?
Or we might discover the exact opposite – that coffee simply works for us.
Both possibilities are, in my opinion, more interesting than spending a lifetime assuming we already know our answer.
Sources
- Gardiner C. et al. The effect of caffeine on subsequent sleep: A systematic review and meta-analysis. Sleep Medicine Reviews, 2023.
- Landolt H.P. et al. Caffeine intake (200 mg) in the morning affects human sleep and EEG power spectra at night. Brain Research, 1995.
- Landolt H.P. et al. Caffeine reduces low-frequency delta activity in the human sleep EEG. Neuropsychopharmacology, 1995.
- Zabelina D.L., Silvia P.J. Percolating ideas: The effects of caffeine on creative thinking and problem solving. Consciousness and Cognition, 2020.
- Juliano L.M., Griffiths R.R. A critical review of caffeine withdrawal. Psychopharmacology, 2004.
- Rogers P.J. et al. Effects of caffeine and caffeine withdrawal on mood and cognitive performance degraded by sleep restriction. Psychopharmacology, 2005.
- Klevebrant L., Frick A. Effects of caffeine on anxiety and panic attacks in patients with panic disorder: A systematic review and meta-analysis. General Hospital Psychiatry, 2022.
- Nordestgaard A.T., Nordestgaard B.G. Coffee intake, cardiovascular disease and all-cause mortality: observational and Mendelian randomization analyses. International Journal of Epidemiology, 2016.