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Why Does Coffee Make Me Sleepy? 5 Reasons Explained


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December 26, 2022

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Imagine, on a busy day, you decide to have a cup of coffee to get rid of sleepiness, and you end up feeling more sleepy than ever. Frustrating, right? 

Many people consume coffee every day to fight off tiredness and improve focus. It’s a widely used beverage all over the world. However, it works differently for everyone. Some people may feel few side effects with multiple cups of coffee, and others may feel various side effects with one cup of coffee. Do you, too, feel that caffeine makes me sleepy? Do you feel tired after drinking coffee?

Continue reading to learn more about caffeine and its effects on sleep. 

Why Does Caffeine Make Me Tired?

Ever wondered why caffeine makes me tired? As per a study, in the USA, the most significant source of caffeine is coffee. Coffee itself is not harmful, but caffeine can make you feel tired as you experience a caffeine crash. Can caffeine make you tired? Yes, sometimes. Caffeine makes you tired due to some factors like:

1. Coffee Blocks Adenosine

Adenosine is a naturally present hormone that makes you sleepy. This hormone controls your sleep-wake cycle. It increases during the awake hours and decreases while you sleep. When you consume coffee, your body absorbs caffeine, and it sticks to your adenosine receptors. 

Caffeine blocks the receptors from receiving adenosine, and that’s why you feel alert after having coffee. After some time, when the caffeine effect wears off, a buildup of adenosine hits you all at once. That’s how caffeine can make you feel more tired. 

2. Caffeine Can Add to Stress

Anyone with stress-induced insomnia knows that stress can keep us awake during the night. When you consume coffee, the stress hormone or cortisol levels increase in your body. When the level is high, you feel stress and anxiety that can keep you awake all night. Although it’s excellent if you wish to stay awake, it can lead to fatigue later during the day.  

study found that consuming caffeine doubled the levels of cortisol and epinephrine in your body. You can feel stressed after the caffeine effect goes away. Ultimately, stress converts into sleepiness, and you start feeling sleepy after coffee. 

3. You Have Built up Your Caffeine Tolerance 

People who consume coffee can build a tolerance to caffeine. As coffee blocks the adenosine receptors, as a result, your body starts producing more adenosine receptors. 

small study was conducted to examine continuous coffee consumption on the cycling of 11 active adults. 

Initially, the participants had higher heart rates and exerted great power after drinking caffeine. After 15 days, the effect of caffeine started to decline. 

If we observe these results, it appears that the effect of caffeine declines with time. 

Although, some researchers contradict this and believe that regular caffeine consumption does not affect how your body metabolizes it. 

4. It’s the Sugar, Not Coffee

Milk, coffee, and sugar together make a perfect cup of coffee. Some of you may like coffee sweetened with honey, whipped cream, or sugar.  As we all know, sugar is infamous for sugar crashes making us sleepy and tired

When you increase your sugar intake, your body produces insulin to create a balance. But the insulin makes your blood sugar drop, which is your primary energy source.

With a drop in blood sugar, you get tired, anxious, and hungry. It’s not only the case with coffee, but sweet food items like candies, chocolates, and alike can have a similar effect. 

You should consume more protein to balance a sugar crash. 

5. Coffee Is a Diuretic

Do you feel like going to the toilet more often after having coffee? That’s because coffee is a diuretic. That means it helps you get rid of water and salt in your body. Coffee consumption increases the risk of dehydration. 

If you consume coffee without drinking sufficient water, you can feel the symptoms of dehydration, like:

  • Tiredness
  • Confusion
  • Dryness (mouth and skin)
  • Dizziness
  • Thirst

Make sure you drink enough water daily with caffeine consumption. An average adult should have a water intake of 2.72 liters to 3.66 liters per day. 

How to Minimize the Effect of Caffeine on Sleep?

It’s not easy to avoid coffee. The hectic days and quiet afternoons call for a perfect cup of coffee. Here are some tips to minimize the side effects of coffee consumption.

1. Check Your Caffeine Intake

The Food and Drug Association (FDA) suggests adults do not consume more than 0.4 grams of caffeine daily.

2. Avoid Sugar

The sweet taste of your drink can lead to a troubling sugar crash later on. Try to avoid sugar in your beverage to prevent a sugar crash.

3. Stay Hydrated

It’s essential to be hydrated, especially if you are a coffee consumer, as coffee is a diuretic. Aim to drink at least 2.72 liters to 3.66 liters of water every day. 

4. Have Decaf in the Afternoon

Coffee stays in your body for 10 hours. That’s why having coffee before bed can keep you awake all night. You can switch to decaf or tea in the afternoon to avoid the circumstances. That’s why one should avoid coffee at night. 

Caffeine Limits to Consider

 Dietary Guidelines for Americans suggest adults consume 0.4 grams of caffeine per day. However, there are no recommended guidelines for children and teenagers, but caffeine has more adverse effects on young children, according to research. 

In pregnant women’s bodies, caffeine stays longer than usual. An association, ACOG, suggests pregnant women consume no more than 200mg of caffeine. 

How Long Does It Take for Caffeine to Kick In?

Coffee begins showing its effects within 15 minutes of consumption and generally reaches its peak after an hour and stays for several hours. Even after 6 hours of caffeine intake, half of it is still in your body. 

How Long Does Caffeine Stay in Your System?

Caffeine stays in your system for around 10 hours. During pregnancy, it lasts for a longer period, about 16 hours. Avoid consuming caffeine after 4 pm so you can have a quality sleep at night. 


We hope you learned why caffeine puts me to sleep? For many people, it’s difficult to survive a day without coffee. Coffee is not bad for you if you take care of factors like coffee, sugar, and proper hydration. 


Yes, you should avoid coffee after 4 pm. Consuming coffee around your bedtime disrupts your sleep-wake cycle, keeping you awake all night. 

Yes, caffeine can have the opposite effect if you:

  • Consume more than 400 mg of caffeine every day.
  • Don’t drink plenty of water.
  • Have a lot of sugar in your coffee.

There is not any effective remedy to completely get rid of caffeine from your system. However, you can reduce the side effects of caffeine by being hydrated, going on a walk, and eating healthy food.

No, a moderate amount of coffee or tea per day, i.e4 to 5 cups, isn’t bad for your heart.

When you consume caffeine, the effects start to show in 15 minutes and reach a peak after one hour. 

When you consume coffee, the cortisol levels in your body increase, which eventually increases stress and anxiety levels, consuming more than recommended caffeine can lead to anxiety. 

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