Why Doesn’t Caffeine Give Me Energy? Top 6 Reasons!

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As a stimulant, caffeine can increase energy levels and make you feel more alert. In the United States, coffee is the largest source of caffeine in the diet. According to the National Coffee Trends 2022 report, about 66% of Americans drink coffee daily.

Some people react differently to caffeine and feel tired after just one cup. We can often hear people saying that I feel like coffee doesn’t give me the energy I need!

But it’s not really the Java that does not give you energy and makes you tired. It’s the way caffeine affects your body that can make you sleepy. Read on to learn more.

Why Doesn’t Caffeine Give Me Energy?

1. Caffeine Tolerance

Lots of coffee cups on white background

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You may not feel the stimulating effect of your cup of coffee because you have developed caffeine tolerance. As you consume coffee more or more frequently, your body becomes less sensitive to it. As a result, the amount of caffeine needed to achieve the same effect as before increases.

The maximum recommended dose of caffeine is 400 mg per day, which is equivalent to about four cups of coffee. If you no longer feel the stimulating effects of caffeine when you reach this limit, you may have developed too high a tolerance. Consuming more than this can cause adverse effects such as headaches or insomnia.

If you no longer respond to caffeine, try taking a break. People can reduce their caffeine tolerance by cutting back on caffeine consumption. Taking a caffeine break can help the body become more sensitive to the effects of caffeine.

However, if you’re addicted to caffeine, quick caffeine withdrawals can lead to a caffeine hangover. This condition has common symptoms of headaches and irritability. Therefore, it is best to reduce your caffeine intake slowly. The length of the break depends on how addicted you are, and a nutritionist can give you an individualized assessment.

2. Fatigue

Alarm clock at 7 am

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Caffeine is not a remedy for fatigue or lack of sleep. If someone is very tired, coffee may not wake them up, and the body needs adequate sleep.

If you haven’t been getting enough uninterrupted rest lately, try going to bed earlier with sleep meditation.

3. Sugar in the Coffee

If you like to add extra sugar to your cup, you may experience a regular sugar crash after drinking your coffee. This added sugar can be in the form of whipped cream or syrup. These are common in specialty coffee drinks. Not surprisingly, both Starbucks and Dunkin’ are actively promoting larger beverages and more and more additives.

But what exactly happens when you drink a large coffee drink with plenty of sugar? The body processes sugar much quicker than caffeine. Once the body has used up the sugar, there can be a drop in energy. How quickly this happens depends on the individual. It can occur within 60 to 90 minutes of ingesting sugar.

4. Adenosine

Adenosine is a chemical in the central nervous system that regulates the sleep-wake rhythm. When you’re awake during the day, adenosine levels rise. This might be causing sleepiness by suppressing the activity of basal forebrain cells. Once you fall asleep, adenosine levels decrease.

The caffeine in coffee blocks the brain’s adenosine receptors, so they can no longer take up adenosine. But it does not stop the actual production of adenosine or the ability to make more adenosine receptors. When the effects of caffeine start to wear off, adenosine accumulates and tries to bind to its receptors. This can lead to fatigue.

5. Dehydration

Caffeine is a diuretic, and high coffee consumption increases the risk of dehydration. However, many scientists argue that caffeinated beverages do not affect long-term urine production any differently than other beverages.

If you find that drinking coffee makes you urinate more frequently than usual, you may get into a cycle of dehydration that makes you even more tired.

First, your body loses water when you go to the bathroom. Water loss can reduce the amount of fluid in your blood. This can affect the way your cardiovascular system responds to maintain blood pressure and flow. Dehydration can cause low blood pressure and a rapid heart rate. This can lead to feelings of sluggishness and fatigue.

When the body’s cells are dehydrated, they lose fluid volume. When this affects their normal functioning, it can also lead to a feeling of sluggishness. It’s normal to reach for another cup of coffee to counteract this sluggishness, but this can start the cycle all over again.

Caffeine also causes vasoconstriction. This means that it causes certain blood vessels to constrict. This can change the blood flow in different parts of the body. If you drink a lot of coffee, you may not drink as much water as you should to rehydrate yourself.

6. Genetics

If you don’t feel the stimulating effects of caffeine, it may be due to your genes:

Researchers found that about 10% of people carry a gene that makes them hypersensitive to caffeine. This allows them to consume high levels of caffeine without feeling any effect.

After ingesting caffeine, it takes about an hour for the body to absorb it. The caffeine molecules then travel quickly to the brain. They bind to receptors typically paired with adenosine, a neurotransmitter that promotes sleep. This prevents adenosine from reaching those receptors, which inhibits sleepiness.

Your genetics can determine caffeine sensitivity by influencing how your body’s adenosine receptors can bind to caffeine molecules.

How to Minimize these Effects?

If you don’t want to give up coffee, try to stick to the recommendations for daily consumption. Up to 400 milligrams of caffeine per day is considered moderate. That equates to two to four cups of brewed coffee per day, depending on your coffee blend.

To further reduce fatigue, you should avoid coffee drinks with sugary syrup and cream. You should also limit the use of sweeteners. Alternating between a cup of coffee and a cup of water can also help. If you usually have an afternoon slump, try switching to decaf coffee after lunch.

Remember that coffee is not the only caffeinated beverage or food. Soft drinks, energy supplements, chocolate, and even some pain relievers contain caffeine. The overall effect of caffeine on the body depends on the total amount supplied to the body from all sources and how often caffeine is taken.


Factors such as excessive caffeine consumption, poor sleep quality, sugar in your coffee, and even genetics can prevent caffeine from having its full effect. Limiting or completely reducing caffeine consumption can help reduce your tolerance.

Adequate rest can also help you feel the stimulus of caffeine better. If you limit yourself to 400 mg of caffeine per day or less and don’t overdo it with added sugar, you should be able to enjoy the energy-boosting benefits of caffeine.

Featured Image Credit: Karolina Grabowska, Pexels