Why doesn’t caffeine affect me

Why doesn’t caffeine affect me?

Expecting to stay awake after taking caffeine in order to finish your work and being surprised that you rather fell asleep just like the usual? Maybe you are wondering why caffeine makes every stay awake for long but seems not to have any effect on you. You are probably asking yourself the question “why doesn’t caffeine affect me?”

It is really baffling to know that caffeine seems to have little or no effect on you. However, this phenomenon can happen, and it is due to some causes and even happen over a period of time.

For some people, it can be a nuisance as caffeine has little or no effect on them, but for others, it can be a blessing. If you find yourself in the first category, this article is for you.

But first, let us take a look at what caffeine is, and how it works, and then we will delve into why it may not affect you.

What is caffeine?

Caffeine is a naturally occurring stimulant that is present in tea leaves, coffee beans, cocoa beans, and kola nuts. It works by activating the brain and central nervous system, which keeps you awake and prevents fatigue.

It is one of the most widely consumed natural stimulants in the world. Today, 80 percent of the world’s population drinks caffeinated beverages on a daily basis (1). 

How does caffeine work?

Caffeine is absorbed readily into the bloodstream after consumption and distributed throughout the body. Caffeine administration affects the functioning of the heart, kidney, respiratory, and nervous systems.

Caffeine’s main effect, however, is on the brain. It works by inhibiting the effects of adenosine, a neurotransmitter that relaxes the brain and causes fatigue (2).

Adenosine levels usually rise throughout the day, making you feel fatigued and driving you to want to sleep.

Caffeine keeps you awake by binding to and inhibiting adenosine receptors in the brain. This action reduces sleepiness by blocking the effects of adenosine (3).

It may also raise blood adrenaline levels and boost dopamine and norepinephrine neurotransmitter activity in the brain. This combination increases brain stimulation and enhances arousal, alertness, and focus.

Caffeine is commonly referred to as a psychoactive substance because of its effects on the brain. Caffeine, on the other hand, has a short half-life. For example, the amount present in one cup of coffee can reach the bloodstream in as little as 20 minutes and take up to an hour to attain maximum impact (4).

Foods and drinks that contain caffeine 

Caffeine can be found in the seeds, nuts, and leaves of a variety of plants and has a bitter taste enough to inhibit pest activity (5). Caffeinated foods and beverages are made from these natural sources, which are gathered and processed. Below are the concentration of caffeine in selected beverages

Amount of caffeine in popular beverages

Sources of caffeineCaffeine (mg)/ 8 oz (240ml) serving
Plain, brewed 133
Caffeine (mg/8 ounce) comparison in different beverages (6)
Sources of caffeineCaffeine (mg)/ 8 oz (240ml) serving
Brewed 53
Green 45 
Black 47
Caffeine (mg/8 ounce) comparison in different beverages (6)
Soft drinks
Sources of caffeineCaffeine (mg)/ 8 oz (240ml) serving
Coca-cola classic 23
Pepsi cola 25
Diet coke 31
Caffeine (mg/8 ounce) comparison in different beverages (6)
Energy drinks
Sources of caffeineCaffeine (mg)/ 8 oz (240ml) serving
Red Bull 76
Rockstar 80
Caffeine (mg/8 ounce) comparison in different beverages (6)

Benefits of caffeine 

Caffeine has been shown to

  • increase mood,
  • reduce depression risk,
  • boost brain function, and
  • protect against Alzheimer’s and Parkinson’s disease (6, 7, 8, 9, 10).

Caffeine can block the chemical adenosine, which is involved in brain signaling. Other signaling chemicals like dopamine and norepinephrine are increased as a result of this. This shift in brain messaging is thought to improve your mood and cognitive abilities (11, 12).

In addition, a study found that drinking 2–3 cups of caffeinated coffee per day (equivalent to 200–300 mg of caffeine) reduced the risk of suicide by 45 percent (13).

Caffeine may improve metabolism by up to 11% and fat burning by up to 13% due to its capacity to activate the central nervous system. In practice, ingesting 300 mg of caffeine per day can help you burn an additional 79 calories each day (14, 15).

Caffeine may boost the consumption of fat as a source of energy during exercise. This is advantageous because it extends the life of glucose stored in muscles, possibly delaying the time it takes your muscles to exhaustion. Caffeine may also help with muscular contractions and fatigue tolerance (16).

Caffeine may also have protective effects against heart diseases and diabetes (17, 18

Side effects of caffeine

Excess intake of caffeine can lead to side effects like any other drink or food. Some of the side effects associated with the intake of caffeine are:

Why doesn’t caffeine affect me?

Some people seem not to react to caffeine. This is something that can occur for many reasons and in this section of the article, we will explore the reasons why caffeine doesn’t affect some people unlike how it works on other people. 

Here are some of the reasons why caffeine doesn’t affect you:

  • Taking too much caffeine
  • Taking too little caffeine
  • Your genetic makeup
  • Having high tolerance to caffeine
  • Lack of sleep

Now, let’s take these reasons one after the other and explain why any of them may be the reason why caffeine does not affect you the way you want.

Excess caffeine: Taking too much caffeine

Caffeine is no exception to the rule that too much of anything is never a good thing. If you drink too much coffee, you risk not just having a heart attack, but you also risk caffeine losing its effect on you.

You will begin to experience serious adverse effects once you reach a specific dosage (usually 400 mg per day). You will become agitated, and your sleep will suffer as a result 

Too little caffeine 

If you consider your weight, age, and other medical issues, your caffeine consumption might not be enough. All of these things can affect your body’s ability to digest coffee, and you may be underestimating your abilities. Just like how much alcohol you can handle depends on your height, weight, and age, the same can be said for caffeine. If you are a big person, try increasing the amount you drink each time until you get the desired result.


Our DNA has a strain that influences how we process caffeine. Unfortunately, some people’s DNA is such that the effect of caffeine on them is not as prominent as that of the others. If you find yourself within this category then it may be the reason caffeine doesn’t affect you the way you want.

If this is why caffeine does not affect you, there is little to nothing you can do to change it.

High tolerance levels

Caffeine tolerance can be built over time. When caffeine is continuously taken, the body may build some form of tolerance. This means that the same amount of caffeine that use to give you an effect no longer stimulates you and you will have to take an excess of that to achieve the same results.

You will need more and more coffee to be awake and aware after a while, so it may be preferable for you to simply quit drinking. You may reach a point when the caffeine you drink is causing you more harm than benefit.

Not enough sleep 

Caffeine may not awaken you if you are exceedingly tired and worn out, and your body needs proper sleep. This only happens after a long period of sleep deprivation, although merely three days can be enough (22).

The takeaway from this article 

Caffeine not affecting you is something that can occur. There are a lot of factors that can cause caffeine to not work on you. Excess intake, inadequate intake, build-up of tolerance, and genetics are some of the factors that can prevent caffeine from affecting you. 


Michael Sarfo
Content Creator at Wapomu

Michael Sarfo is a graduate of the University of Ghana, Legon. He is a content creator for enochkabange.com and a writer for Wapomu

Dr. Solomon Kwesi Otchere (Pharmacist)

Dr. Solomon Kwesi Otchere is a Pharmacist by profession in Ghana. He is passionate about informed healthy lifestyle and diet options necessary for preventing many disease conditions. He also empowers patients and clients to make savvy choices on medications needful to promote good health.

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