Why does Coffee make Me Sleepy? 8 Possible Reasons Why

9 min read NOV 02, 2022

Coffee and other caffeinated drinks are the best energy drinks around the globe. We usually associate drinking coffee with increased alertness. But sometimes, coffee has the opposite effect on us. You may in fact drink that cup of coffee and feel sleepy instead.

So, you start wondering...why would coffee make me tired?

As coffee increases our alertness and boosts our energy, it does contribute to feeling tired later on. When the coffee wears off, the body realizes it has increased stress levels during the hyperactivity session. To counter the stress effect, you will get sleepy and might actually go into a deep sleep sooner.

While drinking coffee blocks the brain's adenosine receptors, which contribute to feeling fatigue, caffeine, as we all know, can also give us that much needed energy boost. 

Listening to your body and finding that balance when drinking our beloved brew is key.

So, if you want to know more about why coffee makes you sleepy, we've got you covered!

So, Why does Coffee make You Sleepy?

There are various reasons why coffee makes us sleepy after drinking it. Here are some of the main causes that can contribute to your drowsiness after you sip on that morning cup of goodness.

1 - Coffee has brain-blocking abilities.

Our bodies produce a chemical substance called adenosine. This neurotransmitter works by affecting the physical and cognitive receptors triggering fatigue during normal body functioning.

Coffee, unlike most caffeinated beverages, does something to this chemical substance. Caffeine binds to the adenosine receptors in the brain. Therefore, high doses of caffeine affect how your brain functions.

The blocking effect occurs after the cup of coffee enters our blood circulation system. It gets absorbed and transmitted to various body parts, including our brains. After coffee blocks these adenosine receptors in the brain, you fail to experience the chronic fatigue caused by your metabolism.

The short-term effect gives us that boost, but...

While the body produces adenosine, its receptors don't register its effect. So, when coffee wears off, the body has an excess of this chemical substance. The receptors register the caffeine effect of the chemical substance, and you begin to feel sleepy as the body tries to balance the stress.

Our body's reaction often leads us to consuming even more coffee and caffeine to counteract the drowsiness. You know, that afternoon latte that helps push us through those final work hours...?

2 - You could be dehydrated.

Another reason you may feel sleepy after drinking coffee is as simple as being dehydrated. A lot of people don't think about coffee contributing to dehydration, especially since each cup of brew is essentially mixed with water...But regularly consuming coffee has effects on your body which can contribute to this.

Ever notice how that cup of coffee, or tea, "runs right through you?" Meaning, you usually need to make a trip to the bathroom not long after finishing you drink?

Caffeine intake triggers a constant urge to pee. As you take more energy drinks packed full of caffeine, your desire to pee will also increase.

Constantly emptying your bladder can lead to dehydration, which then can lead to feelings of tiredness. 

Dehydration lowers your blood circulation rate, attributing to low blood pressure. The effects of this can cause you to feel sluggish, tired, or sleepy after drinking coffee.

How do you fight coffee dehydration?

The best technique to stop feeling sleepy after coffee is to find a balance and increase your water intake. Drinking water helps boost your water levels and helps to maintain proper blood circulation.

One sign that you are dehydrated is the development of a dry mouth, especially on the lips. If constantly sipping on water all day doesn't appeal to you, water-dense fruits make an excellent choice for staying hydrated.

If you need to fall asleep, taking a nap after hydrating yourself is a good way to help regulate the stress hormone as well.

3 - The quality of coffee you are drinking. 

Quality coffee beans guarantee quality coffee. Like green tea, coffee makes us more alert and may have several caffeine effects, especially during waking hours.

Adverse caffeine effects rely on quality most of the time. Coffee specialists have found that some coffee in the local supermarkets doesn't reach the required quality. If this sub-standard coffee interferes with the brain receptors, you may get sleepy sooner after taking it.

The quick sleepy effect may also be attributed to moldy coffee. If the coffee gets stored in poor conditions, it may be easy to develop mycotoxins. Mycotoxins chemical results from fungi and causes extreme fatigue when the caffeine wears off.

Our bodies have varying caffeine tolerance, and poor-quality caffeine drinks lower this tolerance. You may therefore feel sleepy faster. 

4 - Your coffee might contain too much sugar.

Have you heard the term sugar crash? If you love your coffee with the added syrups or sugar cubes (like many of us do), you might be experiencing a caffeine-sugar crash. Some coffee drinks like peppermint mocha and frappuccino contain high sugar levels impacting your blood glucose. A sweet snack has a similar effect.

Some other coffee beverages use whipped cream, which also causes high blood sugar loads. The sugar load proves so high that most people refer to the drinks as "sugar splashed with coffee." The body's energy level might also spike when the blood sugar level spikes.

The sugar crash happens because sugar gets absorbed in our bodies faster than coffee. Excessive sugar overload causes fatigue which later makes you feel sleepy. With too much caffeine intake, coffee binds the brain receptors registering fatigue. Since these drinks contain less coffee, the caffeine crash doesn't occur. We may blame your feeling sleepy on the high blood glucose levels. 

5 - Coffee induces stress.

While most doctors attribute stress to mental health, other medical professionals may attribute stress to coffee intake. Ingested caffeine from coffee might cause havoc in your body. Typically, when the body gets under stress, it produces the stress hormone cortisol. This hormone triggers fatigue and a sleepy feeling.

If you consume caffeine in coffee, the body produces the cortisol hormone. This hormone puts your body in stress mode. The caffeine blocks more adenosine receptors with every brain blood flow preventing fatigue.

Therefore, you stay awake more. When the caffeine wears off, you feel tired and sleepy immediately. If you feel tired or sleepy at night, we recommend you get a good night's sleep to help your body refresh.  

6 - You have an underlying medical condition.

Have you noticed that you get sleepy after drinking coffee when you are sick? The body’s coffee tolerance is at its lowest during this period. During this period, your central nervous system functions maximally to keep the body balanced.

Coffee consumption during this time may bring your body to a breaking point. The body’s brain's adenosine receptors get blocked. As the body fights the disease, it fatigues, but the coffee has blocked the fatigue receptors.

After coffee gets depleted in the body, the excessive adenosine buildup causes stress. Stress increases the hormone cortisol and further fatigue. These competing body functions make you feel sleepy.

6 - It could be the milk and not the coffee.

Like sugary drinks, milk added to your cup of Joe might cause a sleepy effect. Milk contains high levels of the amino acid - Tryptophan. This amino acid helps the body produce a neurotransmitter called serotonin.

Serotonin causes a relaxation feeling that gets attributed to falling asleep faster. A glass of milk before bed works miracles if you suffer from anxiety and sleep disorders. In this regard, if you add milk to your cup of coffee, it might make you feel sleepy within a few hours.

Another theory relates warm milk to triggering the relaxation feeling that occurs during breastfeeding times. When you add milk when drinking coffee, the body translates the warm milk to the effect caused by breastfeeding before bedtime. This diuretic effect significantly causes a sleepy effect after taking warm milky coffee.

7 - You could be suffering from caffeine withdrawal symptoms.

If you were a regular coffee consumer who has recently stopped, you might suffer from withdrawal symptoms. When you drink coffee regularly and quit, you start experiencing coffee withdrawal symptoms, including feeling sleepy. Without coffee intake, the body has more adenosine receptors in the brain that have not had coffee blocks.

So, the chemical adenosine significantly affects the brain and registers fatigue more than it used to. You start feeling sleepy without taking that cup of coffee.

Other Caffeine Withdrawal Symptoms include:

  • Irritability
  • Poor concentration
  • Nausea
  • Headaches

These withdrawal symptoms occur within the first 12 to 24 hours of not having coffee. If you have plans to quit coffee, a gradual approach works better. You may shift to green tea, which has less caffeine, or substituting one of your normal cups of coffee for a decaf option. You will find it easier to cut it back until you eventually stop consuming caffeine.

Frequently Asked Questions

Does caffeine make you sleepy if you have ADHD?

Studies show that caffeine consumption does not affect people with ADHD.

They may not feel the same way other people feel. It doesn't make them switch on, jittery or sleepy.

Can caffeine have the opposite effect?

Coffee and other caffeinated beverages often cause the opposite effect on most people. Instead of boosting energy levels and causing a high alert effect, caffeine may affect people by causing rebound fatigue after wearing off. The opposite effect makes you feel tired and sleepy.

What are the side effects of too much caffeine?

Too much caffeine might cause an irregular sleep-wake cycle, high blood pressure, muscle breakdown, and digestive issues. Therefore, visit a medical professional if symptoms persist. They may also offer some replacement advice on caffeine boost products.

Final Thoughts

Coffee is among the world's leading caffeinated drinks, with recent studies showing that coffee consumption may reduce liver cancer progression by up to 43%. Ground coffee beans and light roast produce the best effect for health benefits compared to instant coffee.

However, take note to consume the right amount of coffee daily. Too much coffee something to be aware of. As with most things, find a balance!

So, if drinking coffee makes you sleepy, don't worry. You will feel better when the caffeine crash ends since caffeine wear resets your brain chemicals. Also, a certified sleep coach might be of help if caffeine consumption threatens your health.  

"Medical Disclaimer
This content is for informational and educational purposes only. It is not intended to provide medical advice or to take the place of such advice or treatment from a personal physician. All readers/viewers of this content are advised to consult their doctors or qualified health professionals regarding specific health questions. Neither Dr. Charles Livingston nor the publisher of this content takes responsibility for possible health consequences of any person or persons reading or following the information in this educational content. All viewers of this content, especially those taking prescription or over-the-counter medications, should consult their physicians before beginning any nutrition, supplement or lifestyle program."

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