There is an age-old legend about how coffee became the drink we all know and love. The story goes like this.

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In Ethiopia, way back in the 9th century, lived a goat herder named Kaldi. Kaldi noticed that after eating the cherries of a certain tree, his goats became super energetic and didn’t want to sleep at night. Kaldi told this to the abbot of the nearby monastery, who used these cherries to brew tea. The abbot found that the drink made from these cherries kept him awake and more alert during the long hours of nighttime prayer. He told others of his discovery and the rest is history!

The alertness given to the abbot by the coffee isn’t given to everyone. In fact, some people report feeling more tired after drinking a cup of coffee. Others feel like a cup of coffee no longer provides the kick like it used to.

Let’s dig in and see how we might be able to fix the issue of coffee making you tired and why it happens in the first place.

Why Coffee Makes You Tired

Blocks Adenosine Receptors

While it might sound contrary to what we’ve always been taught, coffee doesn’t, in fact, wake us up. What it does do, though, is prevent us from getting tired by blocking the adenosine receptors in the brain. Because caffeine has a similar structure to adenosine, a natural sedative produced in the brain that makes us feel sleepy, it can block these receptors. Caffeine and adenosine compete for a place within these receptors — a competition that caffeine usually wins. Without caffeine, adenosine can freely occupy these receptors, which will, in turn, make us feel tired.

Eventually, this blocking effect can decrease as you become less sensitive to caffeine.

Coffee Is a Diuretic

Dehydration is a very common cause of tiredness. And coffee, or the caffeine in coffee more specifically, acts as a mild diuretic. What this means is that coffee containing caffeine will make you need to pee more often. If you are not replacing these fluids by drinking water, you might become dehydrated. As well as increasing the amount you pee, caffeine can also activate your bowel and make you poop!

Tolerance to Caffeine

Studies have shown that people who drink a lot of caffeine build a tolerance to its stimulatory effects. This tolerance can kick in so quickly that someone not used to caffeine can become desensitized in less than 4 days! With coffee giving you less and less of boost the more you drink, you may still feel tired shortly after drinking it.

Increases Blood Sugar Levels

In large enough doses, caffeine can reduce insulin sensitivity. This can lead to the body producing more insulin, leading to higher levels of both glucose and insulin.

While caffeine may slightly raise blood sugar levels, for the average coffee drinker, the increase in blood sugar is most likely thanks to the sugar they add to their morning cup.

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Sugar You Add, Not the Coffee

Why Coffee Makes You Tired - Sugar You Add

When you intake a lot of sugar, say, when you drink a cup of coffee with a few teaspoons inside, your body rapidly produces insulin to try to keep your levels consistent. This then causes your blood glucose levels to drop, which will often result in a decrease in energy. The dreaded sugar crash!

It’s the Mold, Not the Coffee

If you are drinking poor quality coffee and feel like it’s sapping your energy, there is a high chance that the coffee contains small amounts of mycotoxins created by mold. The ingestion of these mycotoxins can cause anything from brain fog and fatigue to inflammation and asthma.

While it’s hard to tell exactly which coffees contain these mycotoxins and which coffees don’t, they are most commonly found in poor quality coffee, especially coffees of the robusta species. A premium low acid coffee, like the coffees made by bulletproof, specifically made to be mold-free.

Caffeine Withdrawal Symptom

When a coffee drinker goes a few days without drinking caffeine, they may experience caffeine withdrawal. This happens mostly when caffeine is cut completely out of the diet, cold turkey. Common symptoms of caffeine withdrawal include constipation, headaches, fatigue, and irritability.

How Does Caffeine Affect Your Body

When we drink a cup of coffee, what exactly happens within the body? Most of us feel a buzz, increased alertness, and maybe experience a better mood — but why does this happen?

It’s all to do with the structure of the caffeine molecule.

The caffeine molecule has a very similar structure to adenosine — a powerful sedative that our brain produces. When adenosine fills the adenosine receptors within the brain, we start to feel sleepy.

Because caffeine has a similar structure to adenosine, it too can fill these adenosine receptors. The adenosine and the caffeine compete for a place in these receptors. And caffeine is usually the winner. Blocking these receptors essentially stops us from feeling tired.

As an added bonus, by blocking adenosine, caffeine can promote the brain’s production of two natural stimulants — dopamine and glutamine. Both of these can help improve mood and decrease the risk of depression.

Other Effects of Coffee

Aside from making you either tired or super alert, coffee can have a bunch of other effects too. As always, your mileage may vary. Many people experience none of the effects mentioned here, while others experience them all and more.


Drinking too much coffee can affect your sleep. This is really no surprise because, as we’ve just discussed, caffeine actively blocks you from becoming sleepy.

To avoid having issues sleeping, limit yourself to no more coffee 4-6 hours before bed. So if your bedtime is at 11 pm, think about having that last coffee at around 6 pm or 8 at the latest.


There is no evidence to suggest that caffeine actually creates anxiety. But as a stimulant, it can increase the symptoms in already anxious people. Because caffeine elevates cortisol secretion, otherwise known as the ‘stress hormone,’ people not used to caffeine can feel anxious after drinking a cup.

Cardiovascular Effects

Other Effects of Coffee - Cardiovascular Effects

The way that caffeine affects our cardiovascular system is largely dependent on the amount of caffeine that we ingest. At high levels, caffeine can increase the calcium within the cells of the heart. This increase can affect the hearts pumping action. Caffeine can also aid the release of norepinephrine, which can increase the rate and force of the contractions of the heart. Norepinephrine has a stimulating effect, similar to that of adrenaline.

Cancer Prevention

While there have been thousands of studies to both prove and disprove coffee’s role in cancer, there has been no real conclusive evidence to show either for or against. Some studies have suggested that coffee may lower the risk of some cancers, including endometrial cancer, prostate cancer, and liver cancer.

How to Avoid Being Tired After Drinking Coffee

Many of the facts we’ve looked at so far might make coffee look like the bag guy (or girl). But the thing is, many of these downsides are directed at high levels of caffeine only. A safe amount of caffeine for a healthy adult is around 400mg of caffeine. That’s about the amount in 4 cups of filter coffee.

But 4 cups of coffee might still sound like quite a lot to many people. Let’s take a look at how you can enjoy your coffee without feeling tired afterward.

Sip Smarter

Try spacing your cups of coffee out. Instead of drinking 2 or 3 cups of coffee right away in the morning, try just drinking one. Go for that second cup a few hours later. Spreading out your caffeine intake might help reduce the amount of caffeine building up in your system.

The caffeine in coffee beans will give you an energy boost, but too much might make your energy levels spike, then crash hard shortly after.


To avoid caffeine’s dehydrating effects, we need to make sure that we hydrate as we are drinking. So long as we hydrate adequately, we should be able to avoid feeling tired due to dehydration.

Make sure you drink water before and in-between each cup of coffee. Don’t let coffee or soda be the only fluids you are drinking throughout the day. Aim for around 3 liters of water a day.

Skip the Sugar

One of the biggest reasons people feel tired, or crash hard after drinking coffee, is the sugar they add to the coffee— not the coffee itself. Try drinking coffee without sugar.

Good coffee should already be sweet. Costa Rican coffee is known for its unique taste and doesn’t really require any sugar. Try going beyond basic coffee types and you might find that with the right coffee, the need for sugar disappears.

If you feel like you can’t go without something sweet, try a natural coffee creamer. Something like grass-fed cream can add a little sweetness to your coffee. There are also coffee creamers suitable for vegans available. Even honey is a healthier alternative to white or raw sugar.

Evaluate Your Lifestyle

How to Avoid Being Tired After Drinking Coffee

It might be tempting to buy a huge 20oz cup and heat up your coffee with a warmer as you sip on it throughout the day. But this huge amount of coffee, combined with sitting at a desk for long periods of time can really take a toll on your overall health.

Getting up to walk about, to go outside and pick up a coffee — these provide a much-needed break from the office life. Make sure you move around in the day.

Daily exercise, eating well and taking regular breaks from sitting can all improve your overall energy levels.

Switch to Decaf

If caffeine is really affecting your energy levels, yet you love the taste of coffee, try a cup of decaf! The quality of decaf coffee has made leaps and bound recently. It is now possible to get a truly delicious cup of decaf coffee.

Try decaf coffees with different roast levels. French roast coffee has a better aroma and is much more intense and bitter. Light roasted will usually have less of an aroma but allows the natural flavors of the coffee to shine through.

Do’s and Don’ts With Coffee


  • Do try organic coffee beans. Organic beans contain more antioxidants, which can increase overall health.
  • Do make sure you drink water in-between coffees. Aim for around 3 liters of water a day
  • Do get enough exercise throughout the day. We should never rely on coffee to give us the energy we need. Daily exercise, no matter how short in duration, can have huge health benefits.
  • Do drink quality coffee. High-quality coffee not only requires less sugar to make it sweet, but it also has a lower chance of containing mold.
  • Do measure out your coffee. If you are sensitive to caffeine, measure coffee with precision using the world’s best coffee scale. This will give you more control over how much caffeine you are taking in.


  • Don’t drink too much coffee. Around 4 cups is a healthy amount of coffee for most healthy adults.
  • Don’t add loads of sugar to your coffee. Try drinking coffee that is of better quality. It will most likely be naturally sweeter and less bitter.
  • Don’t drink your daily allowance of coffee in a short amount of time. Spread your coffee consumption out throughout the day.

FAQ About Why Coffee Makes You Tired

FAQ About Why Coffee Makes You Tired

Can caffeine have the opposite effect?

It is easy to build up a tolerance and get used to the stimulating effect of caffeine. Many people no longer feel energized after a cup of coffee, but they do feel the rebound fatigue afterward. This rebound fatigue can make it feel like coffee has the opposite effect.

Why does coffee affect me so much?

The way each person is affected by caffeine all comes down to the way each individual metabolizes caffeine. Some people metabolize it quickly, while for others, it takes far longer. For people who metabolize it slowly, they may feel the effects of caffeine more intensely and also for longer.

Is coffee a stimulant or a depressant?

Coffee contains caffeine, which is a mild stimulant. In healthy doses, caffeine can give energy, improve mood, and aid athletic performance. In large amounts, however, caffeine can prevent sleep, and its withdrawal symptoms can lead to mood swings, irritation, and lack of energy.

Does coffee make you energetic?

By keeping you from getting tired, coffee can make you feel more energetic. Coffee also speeds up the messages between our brain and body, helping us feel more alert.

How long does it take for coffee to take effect?

Caffeine reaches peak levels in the bloodstream within 30 and 60 minutes after ingesting it. The level of caffeine in the blood drops by half within 5 hours. This means that 5 hours after drinking coffee, the effects of the caffeine will be halved. After 15 hours, there is no longer enough caffeine in your system to have an effect.

How does caffeine affect your sleep?

Caffeine essentially blocks our adenosine receptors. With these receptors being blocked by caffeine, we won’t feel tired. When the effects of caffeine wear off, the adenosine can find it’s way into our adenosine receptors, which in turn will make us feel sleepy.


Coffee is an incredibly personal thing. From the way we brew it to the way we enjoy it and even the way we metabolize, it is different from person to person. Some people can drink five cups a day and don’t get a buzz. Others get jittery after a single cup.

If you are having issues with your coffee intake — maybe coffee makes you tired, or maybe it keeps you up at night — give these tips a try. Just don’t drink too much of it and drink plenty of water!

Photos from: stetsik /, MicEnin /, BrianAJackson /, stokkete / and SarkisSeysian /

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