Why Does Coffee Make Me Sleepy

Why Does Coffee Make Me Sleepy? And The Solution That Works

According to the National Geographic Magazine, Americans drink 150 billion+ cups of coffee each day, with 3 out of 5 people starting each morning with a cup, and the total yearly spending adding up to $164 per head.

We sure love us some coffee.

And, if you walk the streets often, these statistics will come as no surprise. Wherever you go in the US, you are guaranteed to find people toting those humongous Starbucks takeaway cups.

For many, coffee is something of an elixir of life, and the receptacle from where all creativity emanates. However, for others, a dose of java can sometimes have the opposite effect, and complaints of coffee causing sleepiness is surprisingly quite common.

Such episodes immediately create confusion in people as we all have the understanding that caffeine is supposed to keep you awake. Before you go blaming your coffee brew or fearing a severe issue with your body, check out these potential causes.

Here are some common reasons why a stimulant that should increase energy levels and boost alertness may cause drowsiness.

Why Coffee May Make You Even More Tired?

Why Am I So Tired All The Time
Terry Cralle, MS, RN, CPHQ

Coffee-Induced Dehydration

For most people that get sleepy from drinking coffee, the chances are that what they really have is a dehydration problem. In addition to its stimulating properties, for most folks, caffeine also works as a diuretic, increasing the frequency with which they visit the bathroom and putting them at risk for dehydration.

With more trips to the bathroom, the body loses water that is vital to its proper function, the blood thickens and moves slower through your system, delivering less oxygen to your brain and other organs and making you more sluggish and cloudy headed.

Further aggravating issues is the fact that coffee also creates a vasoconstricting effect, which temporarily makes your veins and arteries narrower, further compounding the problem. Consequently, the entire process can happen quite fast, leaving you dehydrated after shortly your Americano double and creating the inkling that coffee is making you sleepy.

Tip: Most people are already not hydrating enough. For best health and proper body function, health authorities typically recommend you consume up to 2 liters (eight 8-ounce glasses) of water per day.

Furthermore, drinking coffee may inhibit your ability to feel thirst, reducing the chances of you drinking water, and helping the dehydration process along.

A Sweet Tooth

coffee heavy in sugar
Terry Cralle, MS, RN, CPHQ

While a homemade cup of vanilla coffee or an iced strawberry frappuccino from Starbucks sure works wonders on the taste buds, the added sweeteners may be the reason for the adverse effect coffee has on you.

Getting a coffee drink that is heavy in sugar may cause sleepiness because of the potential for a sugar crash. Sugar is metabolized by the body significantly faster than caffeine, and at the end of the processing is that energy crash that everyone that has a sweet tooth knows well.

Consequently, with some coffee options, the depleting effect of a sugar crash may hit you way faster than the energy boost from the caffeine, causing fatigue, and possibly making you sleepy.

Furthermore, recent research points to the fact that caffeine itself can spike blood sugar levels. In one 2016 study, researchers found a link between excessive caffeine intake and reduced insulin sensitivity, increased insulin resistance, and higher blood sugar levels.

Even temporary spikes in blood sugar, when high enough, can fatigue, headaches, decrease concentration ability, frequent urination, and by extension, dehydration—all symptoms that can put you in a sleep state.

The Adenosine Block

If the sleepiness from taking coffee only hits you after a few hours, you may be running out of caffeine and running up against the adenosine wall.

Coffee works to keep us awake because the caffeine blocks the adenosine receptors in your brain and prevents them from detecting the crucial chemical messenger.

Adenosine is an endogenous neurotransmitter that causes fatigue, and once caffeine blocks its path, you become temporarily immune to fatigue, resulting in higher energy levels.

However, the processes that are responsible for adenosine do not go to rest during this blockade. They ramp up in an attempt to counteract the perceived adenosine-resistance.

Consequently, when the effects of caffeine wear off, the piling load of adenosine hits you at once, creating the infamous post-caffeine crash and causing sleepiness.

Possible Caffeine Resistance

Another possible reason why you may be experiencing a sleepy crash only a few hours after your espresso shot is the chance that you may have developed some tolerance to caffeine.

Many regular drinkers of caffeinated beverages complain of developing a tolerance to its stimulating effects. One possible explanation for this is the possibility that the frequent adenosine overproduction creates a new baseline. Hence, warranting the need for more coffee intake to get the same effect of a smaller dosage.

However, one research study by the Institute of Medicine Committee on Military Nutrition Research did not find any change in how the body absorbs or metabolizes caffeine even after continuous exposure.

Bad Coffee

Bad Coffee
Terry Cralle, MS, RN, CPHQ

Sometimes the problem is not in how your body reacts but rather in the coffee itself. If you get a cheap batch of coffee that contains impurities like mold, your system may have an adverse reaction to these pollutants, leaving you sluggish, tired, and foggy-headed.

Tip: You can easily avoid this problem by only getting your coffee from reputable brands and opting for only top quality beans.

More: Why Am I So Tired All The Time: 10 Possible Reasons And The Solution

Watch Out for Other Factors

A large cup of coffee is not going to mask other lifestyle choices for long, and if you are perpetually sleep-deprived, dehydrated, or under high-stress, you may find yourself nodding off even after a massive shot of caffeine.

Tip: Other lifestyle choices that can significantly impact your energy levels include sedentary living, poor eating habits, nutrient deficiencies, poor exercise habits, and sleep disorders like sleep apnea.

Read More: How Does Sleep Apnea Impact the Brain?

Coffee May Not Work for You

If you have always had the issue of coffee making you sleep, there is a small chance that you may have a condition that predisposes you to such effects. One such possibility is ADHD, as people with this disorder often report flipped responses to some drugs, with depressants boosting their energy levels and stimulants, creating a relaxing effect.

How to Stop Coffee From Making You Sleepy?

Some changes you can make to your coffee-drinking habits that can mitigate this issue include:


One of the most effective ways to reduce the chances of a coffee-induced slump is to drink enough water. The Department of Health and Human Services recommends you consume up to 2 liters (eight 8-ounce glasses) of water per day for the best health and proper body function.

Black is Better

Avoid the sugar crash by sticking to black coffee whenever possible. A little bit of sweetener may help your coffee go down better, but avoid going too heavy on the syrup or cream to help ensure optimal energy levels after your drink.

Sip Smarter

To reduce the chance of a considerable energy pump and dump, try sipping your coffee over more extended periods instead of gulping it in one go. Furthermore, one effective fix for afternoon slumps is to switch to a less-caffeinated drink after lunch.

Tip: 30 seconds in the microwave is all it takes to rejuvenate a cold cup of coffee


For tolerance-induced slumps, you may need to instigate break periods to help you get better energizing effects from your coffee when you get back on it.

Get Quality Sleep

One surefire way to guarantee higher energy levels throughout the day is to ensure that you get a solid 7-8 hours of sleep every night.

Related: 14 Best Foods To Eat (And 8 To Avoid) Before Bed For Better Sleep


How Long Can Coffee Keep You Awake?

The caffeine active in coffee has a half-life of around 5 hours. However, the peak effects from coffee consumption will hit you within 15-45 of use and begin to degrade rapidly after that 5-hour mark.

Why Does Coffee Hurt My Stomach?

In large doses, coffee can increase the acidity in the stomach, causing stomach aches, especially for people with high stomach acidity or acid reflux.

Why Does Coffee Make You Poop?

Coffee causes increased peristalsis, which reduces the colon’s ability to reabsorb water from fecal matter and can create a laxative effect in some.

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One Comment

  1. For years I suspected that coffee made me sleep or relax. I believe that I do not have to give it up altogether but not drink so much at once. Thank you for this informative article.

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