written by
Deric Loh

Why Does Coffee Make Me Sleepy: The Paradox of Everyone's Favorite Pick-Me-Up

Coffee Dictionary 7 min read

Ah. Coffee. If you consume it like most people do, then you probably feel like it’s the human-equivalent of Ambrosia, food, or rather drink, of the gods. That’s understandable, if you consider why people consume coffee. It is, indeed, a beverage worthy of the gods.

Aside from this, coffee-drinking has become a social event. The rise of coffee bars means more and more people spend their time chatting it up with a friend over their favorite caffeinated beverage. While this tasty beverage may help to increase you social standing, it can also increase something else: fatigue.

That revelation probably wasn’t what you were expecting. After all, a good number of people drink coffee due to its ability to increase the body’s energy levels and cognitive abilities. It does that, too, but under the right circumstances, coffee-drinking also makes you want to take a nap.

Here’s a look at why.

But First, A Little About Coffee and Caffeine

Caffeine is in a number of different foods and drinks. However, an article on Sleep Education says that 54% of caffeine is consumed via coffee. (Tea comes in second at 43%.)

People in the U.S. drink more coffee than other populations around the world. Coffee drinkers in the U.S. drink about 300 mg per person each day. That averages out to be three times higher than the amount of caffeine that people around the world drink. However, drinking 400 mg of coffee of coffee each day is said to have plenty of benefits, like increased cognitive function and energy, a dose of important vitamins, and other benefits.

Want to learn how to differentiate the coffee drinks in your local coffee shops? Be sure to check our guide to coffee drinks here.

The Role of Adenosine

The body makes a number of chemicals that allows it to function properly. These could be the hormones that regulate your hunger or your metabolism or even your sleep. In the case of sleep, the body relies on the chemical adenosine, at least in part, to make sleep happen.

According to Healthline, consuming caffeine disrupts the brain’s ability to absorb adenosine. Under normal circumstances, the amount of this chemical in your body rises during the day, until finally, it reaches a point where you get sleepy. All the while, your brain’s receptors for adenosine take in the chemical until it’s had its fill, so to speak.

However, caffeine blocks the brain’s ability to take in the chemical. That doesn’t mean, however, that the body doesn’t produce adenosine; it just can’t absorb it while caffeine is in the way of those receptors. Eventually, the caffeine blocking the adenosine receptors wears off. Once it does, the brain gets a surge of the chemical, and then the body can finally pick up the chemical that’s been waiting in the wings. That’s why the coffee you’ve turned to as a pick-me-up eventually makes you sleepy.

You can remedy this by drinking decaffeinated coffee. This gives you the coffee experience, but prevents the adenosine block from happening.

Coffee, the Diuretic

As if the adenosine thing weren’t enough, coffee, or more specifically, caffeine has a diuretic effect on the body. Because of this, the body steadily loses its fluid reserves, which causes dehydration, according to WhoWhatWear.

Dehydration eventually produces a chain reaction in the body that increases the heart rate. It also boosts the blood pressure. Both of these reactions make the body feel fatigued due to the extra work it has to do as a result. The solution to this issue lies in you taking in enough non-caffeinated liquids to keep these symptoms at bay.

The Sugar Connection

Mmmmm… There’s nothing quite like that Starbucks frap with lots of whipped cream and chocolate syrup. So, here’s the thing about your favorite delicious treat. The sugar in your coffee also accounts for one of the reasons why you might feel tired after you consume coffee.

Sugar gives you a high, which is one of the reasons why people like it in their coffee. Sugar is a different beast than caffeine in some respects, however. The body metabolizes sugar much more rapidly than it does caffeine, giving you a surge of energy via elevated blood sugar levels. This explains why you experience a crash when your blood sugar takes a dip after the high.

Because people so often drink coffee with sugar, the blood sugar drop from the sugar leaving your system gets associated with the coffee.

It’s a Mask

Caffeine is a trickster. You drink it so that your drowsiness goes away. It does that. However, this is really only a mask of the symptoms of fatigue. According to Livestrong, eventually your caffeine high wears off, and the fatigue that you were already feeling comes back in full force.

In this case, it isn’t that the caffeine makes you sleepy. You were already sleepy. Caffeine pushed that aside for a time. Once the caffeine worked its way out of your system, you get the fatigue back and maybe even more, since you drank the coffee to stop from feeling the tiredness. The real remedy for this sleepiness is sleep, not caffeine.

There is another issue associated with this. Consuming caffeine to counteract tiredness can cause a vicious cycle, where you drink more and more of it to stay awake. Eventually, insomnia can result, making it difficult for you to experience deep, restful sleep.

The Addiction Factor and Adrenal Fatigue

While many people may not look at caffeine consumption with the same eyes as other types of addictions, it is an addiction, nonetheless. This means that your body’s “need” for it will increase as you grow accustomed to drinking it.

You feel fatigued because the dose of caffeine that you consumed in the past doesn’t give you the same boost that it used to. This makes you drink more to get the same boost.

The other thing that happens is that you eventually stimulate the hypothalamus with the caffeine, which in turn releases cortisol. Cortisol is the stress hormone, and after time passes, the adrenals take a beating as a result of continued caffeine consumption.

However, a Harvard article points out an additional point that’s worth thinking about. The overabundance of cortisol motivates you to eat more. If the conditions are right, the cortisol may remain raised, contributing to the cycle, due to an increased desire for caffeine and sugar.

Remedying the Issue

Despite the issues that can come with consuming coffee, it does have its benefits. It can make you feel more alert. It has fat-burning abilities, can make you perform at your peak, and comes with nutrients, like riboflavin (B2), manganese and potassium, and pantothenic acid (B5).

However, caffeinated coffee also comes with some side effects. This article has talked about one of them: fatigue. Consuming 400 mg or less a day provides you with the positive effects of caffeine, while helping you avoid many of the negative side effects. If you can watch your caffeine consumption, then you have a better chance of avoiding the sleepiness that can come with drinking caffeine.

Additionally, it’s important to keep your sugar consumption down. Sugar, in addition to caffeine, will cause a crash that leaves you more tired than when you began. Adding minimal sugar in your coffee helps you sidestep the blood-sugar drop that happens after you have sugar.

It’s also helpful to keep in mind that caffeine has a diuretic effect, which raises your blood pressure and your heartbeat. This side effect is hard on the body, and as a result, the body has to work harder. Both the resulting dehydration and the extra work that your body has to do creates tiredness as well.

Finally, much of the time, you drink coffee because you feel tired. Caffeine doesn’t get rid of the fatigue. It just masks it. While it’s not entirely possible to avoid drinking coffee because you’re tired - sometimes, you have too much work to do - it is important to not substitute coffee drinking for the requisite amount of sleep that your body needs.

If you must occasionally drink coffee to stay awake, that’s one thing. However, if you’re always drinking coffee because you get too little sleep for too many days in a row, then you need to rethink your strategy a bit. By all means, meet up with your friends at your favourite coffee shop. Just make sure that you’re consuming caffeine in balance and that you consume plenty of water and getting plenty of sleep to counteract the effects of the caffeine.

Want to brew your own coffee at home or work instead?

Be sure to check out our other handy coffee guides below:

Coffee Dictionary Health