Effects of Caffeine – An Overview

Caffeine is a fast-acting stimulant that increases heart rate and provides a feeling of well-being and energy.

How long does the effect of caffeine last in our body?

Perhaps one of the most interesting characteristics of caffeine is its rapid effects after consumption.

  • On average, caffeine starts working within 15 minutes.

This explains the popularity of this substance almost everywhere in the world. To understand how long the effects of caffeine last, one must first know that the half-life of this substance is between 3 and 6 hours.

What is the half-life of caffeine?

The term half-life refers to the time it takes for the body to eliminate 50% of a substance that has entered the body.

This means that if you drink a small cup of coffee (236 ml) with breakfast, for example, you are consuming about 96 mg of caffeine.

So, if we know that the half-life of caffeine is 3 to 6 hours, that means there is about 48mg of caffeine in your body at midday.

So as long as caffeine is in your body, it will continue to affect you.

Also, keep in mind that it can take the average person up to 10 hours for caffeine to be completely eliminated from the body.

In other words, if you have a cup of coffee around 7 or 8 a.m., your body won’t eliminate the last bit of caffeine until around 5 or 6 p.m.

Note: On average, caffeine levels peak about 60 minutes after consumption.

Duration of action of caffeine

Knowing how long caffeine lasts can be very useful if you are very sensitive to caffeine, for example.

If so, you might be one of those people who can’t sleep with just one cup of coffee (or less) or have very uncomfortable symptoms like headaches, tremors, etc.

So, if you know the half-life of caffeine, you can change your consumption habits and e.g. B. Prevent your sleep from being disturbed.

Caffeine can affect your sleep patterns

People who are particularly sensitive to caffeine may experience disrupted sleep patterns. A 2013 study even concluded that caffeine consumption also contributes to

6 hours before bedtime can lead to insomnia.

According to this study, you should therefore not consume this substance in the evening hours. However, this does NOT mean that this rule applies to everyone, since everyone has a different metabolism.

For example, an amount of caffeine that causes insomnia in one person may have no effect on another.

Also, some people are more resistant to caffeine, requiring larger amounts of this alkaloid to feel its effects.

Determining the effects of caffeine

Crucial physiological factors are:

  • Weight
  • Size
  • Age
  • Gender
  • Health status

There are other factors that may account for a longer or shorter duration of caffeine’s effects.

The amount of caffeine

An amount of 200-300 mg of caffeine per day is considered moderate caffeine intake. However, it is important to note that not all caffeinated beverages contain the same amount of caffeine.

So, you’re likely to feel the effects of caffeine more if you drink a 16-ounce (large) coffee that contains about 400 mg of caffeine.

On the other hand, if you drink an espresso, which is a highly concentrated coffee that is served in a small cup, you are consuming about 50 mg of caffeine, so the effect of the caffeine may be less.

So, the more caffeine one consumes, the stronger the effect of this alkaloid on the body.

Degree of dependence on coffee

Most people who drink coffee do so for 3 main reasons:

  • Because of the taste
  • Because of the energy
  • A combination of the above factors

Caffeine is addictive, so we always want more of it. But the more caffeine you consume, the more tolerance you can develop for it; this means that your body has become accustomed to consuming this substance on a daily basis.

So, after a while, the same dose of caffeine probably won’t have the same effect.

If you e.g. For example, if you had 1 cup of coffee earlier in the afternoon to recharge your batteries, after a certain time (length depends on the person) you may need 1 or 2 more cups to get the same effect.

This has been studied, particularly in people who drink large amounts of coffee or other caffeinated beverages. So, people with a caffeine tolerance need higher amounts of caffeine to feel the effect.

However, that doesn’t mean we all become addicted to caffeine.

Do you often drink water alongside coffee?

Drinking water is good for our body because it stimulates metabolism and keeps the body in balance.

Water also helps flush caffeine out of the body naturally, preventing buildup of this alkaloid. When your body is hydrated, you can enjoy the benefits of caffeine without facing its negative effects.

That is, as long as you consume caffeine in moderation.

How sensitive are you to caffeine?

Caffeine is a substance that stimulates the release of dopamine in the body, which is why consuming caffeine makes you feel energetic and in a good mood. Caffeine also blocks the action of adenosine in our central nervous system. This makes us feel more alert and focused on the tasks at hand.

For this reason, caffeine is considered a psychoactive substance. On the other hand, your sensitivity to coffee, that is, your body’s predisposition to feel the effects of caffeine to a greater or lesser extent, may depend on your DNA.

Your love of coffee could be rooted in your genes

According to a University of Edinburgh study, people who have the PDSS2 gene appear to be more sensitive to caffeine than people who don’t have it.

This is because the gene appears to decrease the cells’ ability to break down caffeine, making it stay in the body longer.

Therefore, people with this gene need lower doses of caffeine to experience its effects.

Conducting the study on caffeine consumption

The study examined the genetic information of 370 people from a small village in southern Italy and 843 people from six villages in north-eastern Italy.

Study participants underwent multiple tests to determine their genetic makeup. They then completed a survey about their caffeine consumption habits. For example, they were asked to provide information on the number of cups of coffee they drink each day.

The researchers then correlated the responses to the survey with the genetic information of the participants. They found that people with the PDSS2 gene consume less coffee than people who don’t express the gene.

In fact, the study showed that those with the gene consumed at least one cup less coffee on average than the other participants. The researchers then repeated the results of their study, but this time with a group of 1,731 people from the Netherlands.

Which coffee produces which results?

The results were similar, although coffee consumption was slightly lower, perhaps due to the different types of coffee in the two countries.

In Italy, for example, it is common to drink coffee in small espresso cups, while in the Netherlands larger cups, which generally contain more caffeine, are preferred.

This study was published inter alia in the Journal of Scientific Reports and was carried out by both the University of Edinburgh in the UK and the University of Trieste in Italy.

And it’s true that the function of the PDSS2 gene in coffee consumption has not yet been explored. However, the results of this study may add to previous research suggesting that our caffeine consumption habits may be linked to the contents of our DNA.

The importance of the PDSS2 gene

In people who are more sensitive to caffeine, caffeine builds up in their bodies.

This leads to symptoms such as e.g.:

  • Headache
  • Tachycardia (rapid heartbeat)
  • Nervousness or stress
  • Feeling restless (can’t stop moving)
  • Irritability
  • Fatigue.

And it appears that the PDSS2 gene influences this, although it is not yet known exactly how.

Some people should use caffeine with caution

According to the WHO (World Health Organization), there are people who should reduce or stop consuming caffeinated substances because of their health condition.

At the top of the list are pregnant women who should be very careful about the amounts of caffeine they consume due to their pregnancy.

Mainly because it is known that caffeine can cross the placenta, which means that this substance can enter the fetus’ bloodstream and, in high doses, cause serious health problems in newborns.

However, if you suffer from any of the following diseases, such as e.g.:

  • High blood pressure
  • Fast heart rate
  • Gastroesophageal Reflux
  • Peptic ulcer
  • Anxiety
  • Sleep disorders

It is best to consult your doctor to determine the risk/benefit ratio of caffeine consumption for you.

Be careful, caffeine isn’t just found in coffee

Caffeine is a natural substance found in many plants, including coffee, but also in cocoa beans and tea leaves.

In addition, there are artificial forms of caffeine, which are mainly found in carbonated drinks such as Pepsi or Coca-Cola and in energy drinks such as Red Bull and Monster.

So, if you’re particularly sensitive to caffeine, you should avoid, or at least reduce, these foods or beverages as much as possible:

  • Black or green tea
  • Espresso coffee
  • Chocolate
  • Energy drinks
  • Carbonated Beverages
  • Yerba mate
  • Kola nut

Caffeine withdrawal

According to the American Heart Association (AHA), people who drink coffee regularly can experience caffeine withdrawal if they abruptly stop drinking.

So, caffeine withdrawal is a set of symptoms caused by the lack of this alkaloid in the body.

Symptoms typically appear between 12 and 24 hours after you last consumed a caffeinated product.

The most common symptoms of caffeine withdrawal are:

  • Headache
  • Depressions
  • Anxiety
  • Dizziness and tiredness

However, it is worth noting that withdrawal symptoms in moderate caffeine consumers usually improve within 48 hours of the last caffeine ingestion.

On the other hand, those who consume large amounts of caffeine experience the symptoms longer and with greater intensity.

What can you do to stop or reduce caffeine consumption?

The AHA recommends the best way to quit caffeine consumption is to gradually reduce caffeine consumption.

For example, if you drink 4 cups of coffee a day, you can reduce your coffee consumption by 1 cup for a week to help your body get used to using less caffeine.

After the second week you can reduce your daily intake by another cup and so on until you no longer need to drink.

But remember that you should avoid coffee, tea or other caffeinated beverages for at least 3 weeks to get used to it.

Alternatively, you can also replace caffeinated drinks with those with a lower caffeine content.

This might interest you: Does caffeine make you sick? Try these 8 alternatives and you will feel like new.

How much caffeine is in the most common drinks?

After water, coffee and tea are the two most consumed beverages in the world. Below you can find out how much caffeine is in the most common caffeinated beverages.

Also keep in mind that the amount of caffeine in a cup of coffee or tea is affected by many factors, such as: e.g.:

  • The way it is prepared.
  • The type of beans or leaves used.
  • Processing of these leaves or beans.

For example, coffee beans with a medium or low roast have more caffeine than those with a high roast because the heat helps break down the caffeine.

Also, while it may seem contradictory, a cup of espresso contains less caffeine than a cup of regular coffee, despite being more concentrated.

That’s because traditional coffee tends to be served in larger cups, and the more coffee, the more caffeine.

Some medications contain caffeine

Some medications contain caffeine, so it’s a good idea to check the label, especially if you’re looking to reduce your caffeine intake.

So be careful because some over-the-counter pain relievers contain caffeine. For this reason, you should not self-medicate.

Always seek advice from a doctor before making any decision that affects your health.

On the other hand, it should be noted that some herbal supplements contain caffeine, such as guarana.

This compound, which is widely used in beverages and foods, is the plant with the highest caffeine content, even more so than coffee.

Consequences and actions to caffeine

If you are experiencing symptoms related to high caffeine consumption, there are a number of steps you can take to reduce your symptoms.

Keep in mind that there’s no way to speed up the elimination of caffeine once you’ve ingested it, but you can at least make the negative effects more tolerable.

No more caffeinated foods and drinks

If you feel like you’ve had too much caffeine, stop the source—i.e., stop drinking coffee, tea, sodas, or other foods that you know contain caffeine.


If you are not well hydrated, the symptoms associated with excess caffeine can become worse. You may therefore experience increased nervousness and/or increased headaches.

It is therefore advisable to have a bottle of water within reach.

Do sports

If you feel like you can’t stay still in one place because of the caffeine, then why not expend the extra energy by engaging in an exercise program?

This way you can reduce the cravings caused by too much caffeine in your body.