A woman with cup of coffee reclining on bed

Why Does Coffee Make Me Sleepy?

Posted By Vaibhavi K on Jul 24, 2021

Do you drink a cup of coffee while working late into the night? You want the caffeine to keep you alert and awake so you can concentrate on your work without feeling sleepy.

But sometimes you find yourself dozing right after drinking coffee, leaving you wondering- “Why does coffee make me sleepy?” 

But it might not be the coffee. It is the way in which caffeine affects your body.

Caffeine can have a different effect on different people. You might feel tired after a single cup of coffee while someone else might be okay with three to four cups of it. Here are some reasons why your coffee might leave you tired and sleepy.

White coffee cup and coffee beans on burlap textile

Reasons Why Coffee Makes You Sleepy

1. Coffee Blocks the Adenosine Receptors Temporarily

Adenosine is a brain chemical that helps you fall asleep. It increases when you are awake. There are adenosine receptors in your brain to which this chemical binds. And it slows down your brain activity, making you sleepy.

Now, if you are wondering, “Why does caffeine make me tired?” here’s why- Caffeine blocks these adenosine receptors. But it cannot stop the production of adenosine. So, the moment the effect of caffeine fades away, you feel sleepy again. Caffeine gets absorbed within your bloodstream quickly. So, you might feel active just after consuming it. However, you will feel tired as its effect recedes leading to a caffeine crash.

2. Sugar Is the Culprit

Do you love your coffee with sweeteners like honey or sugar? Sometimes it is the sugar that makes you tired. As your blood sugar level rises, your body releases insulin to bring it down. Insulin brings down your blood glucose levels, leading to tiredness.

You may not be adding sweeteners to your coffee but accompanying it with a sweet snack like cookies can have the same impact. So if you have nausea after coffee, it might be due to the sugar crash. A drop in sugar levels can also make you feel dizzy and irritable.

3. Coffee Is Diuretic

If you are addicted to coffee, you might feel the urge to urinate frequently. That is because caffeine is a diuretic. So, don’t be surprised if you find yourself rushing to the washroom after drinking four to five cups of coffee.

If you lose too many fluids, you will experience coffee dehydration. And that will lead to dizziness and fatigue.

Coffee also constricts your blood vessels, reducing the blood flow to various parts of your body. Thus, your blood pressure drops, and you feel fatigued. You might reach out for another cup of coffee to refresh yourself. But that will push you into the vicious cycle making you more tired.

Drink a lot of water to deal with dehydration. Make sure that you also consume fruits and vegetables. That will help you stay hydrated and keep tiredness at bay.

4. Your Coffee Might Contain Mold

Is that a shocking revelation? A 2003 study showed that coffee beans contain mold. Moreover, mycotoxins, a product of microfungi, are also present in coffee beans.

Further research has confirmed a link between mycotoxins and chronic fatigue. So if you feel excessively tired after taking your coffee, it might be due to the mycotoxins. However, most processed coffee contains mycotoxins within legally permissible limits.

5. You May Have Built a Tolerance Towards Caffeine

You might have wondered, “Why does coffee make me sleepy instead of awake?” It can be because you have built a tolerance to caffeine.

Since caffeine blocks your adenosine receptors, the body produces more adenosine to counteract the effects of coffee. A study with eleven participants showed that regular consumption of caffeine made them immune to its energizing effects.

Don’t be surprised if you don’t feel energetic after your favorite cup of coffee anymore. Your body might have got immune to the effects of caffeine.

6. Caffeine Withdrawal Symptoms

Caffeine withdrawal symptoms set in within a day of stopping your coffee consumption. You will feel tired and nauseated.

How can you deal with it? If you are planning to quit caffeine intake, do it gradually. You can reduce your consumption every day. That will give your body the time to adjust.

How to Minimize the Effects of Coffee?

The best way is to give up caffeine consumption altogether but that’s easier said than done. If you can’t quit, you can limit your intake gradually. For instance, drink only a cup of coffee every day instead of two or three. That will reduce the effects of caffeine.

If you feel tired after drinking coffee or are constantly needing a coffee nap then try having it without sweeteners. Additionally, give up on the habit of having sweet snacks with coffee. 

You have to remember, however, that coffee is not the only source of caffeine. If you quit coffee and get addicted to tea, you might experience the same effects. Moreover, energy drinks contain caffeine. So, try to limit their consumption too. You can have green tea to cut down on your caffeine intake.

If caffeine consumption has messed up your sleep schedule, here’s how you can have a peaceful night of sleep.

Caffeine Limits to Consider

Can coffee make you tired? Yes, it can. You know the answer by now. So, it is better to take it within limits.

The Dietary Guidelines for Americans 2015-2020 recommend that an adult should not consume more than 400 mg of caffeine daily. For pregnant women, the quantity should not be more than 200 mg.

The effects of caffeine on children are more severe. So, it is better for them to stay away from caffeinated drinks.

The Bottom Line

The smell of a steaming hot cup of coffee might ease all your burden. But make sure you limit your consumption, and not get addicted to it. Taking coffee and other caffeinated drinks within permissible limits will help you stay away from the ill effects.

Read our blog on here’s how you can fix your sleep schedule.


Can I have a coffee before bed?

Having coffee before bed is not a good idea. It might stimulate your brain, making it hard to fall asleep. Caffeine and insomnia have a longstanding connection.

How long does it take for caffeine to kick in?

You can feel the effects of caffeine within 30 to 45 minutes of consuming it.

Is caffeine bad for your heart?

Caffeine stimulates you and can raise your blood pressure. That can have a negative impact on your heart.

Is it bad to drink coffee at night?

Drinking coffee at night might keep you awake for a while. So, if you have some crucial work to complete, you can consider drinking a cup of coffee. However, it’s better not to drink more than a single cup.

Can coffee affect everyone?

Caffeine acts differently on people. Some need it to start their day on a good note. However, it is you might complain, “Coffee makes me anxious.” while some might say “caffeine makes me sleepy”.

How do you flush caffeine out of your system?

Drinking plenty of water is an excellent way to flush caffeine out of your system.