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What Is A Caffeine Crash? Plus, 4 MD Tips To Prevent It From Happening

Vincent M. Pedre, M.D.
Updated on May 16, 2022
Vincent M. Pedre, M.D.
Board-Certified Internist
By Vincent M. Pedre, M.D.
Board-Certified Internist
Dr. Vincent M. Pedre is a board-certified internist in private practice in New York City since 2004. He serves as medical director of Pedre Integrative Health, president of Dr. Pedre Wellness, and is the author of Happy Gut.

Recently, one of my clients mentioned he had been feeling noticeably tired and irritable, especially in the afternoon. "Around 3 p.m., I get drowsy, and focusing on work feels impossible," he told me during a virtual consultation. The opposite problem occurred at night as he struggled to fall and stay asleep. 

This client believed his problems stemmed from increased levels of stress in his personal life. While I agreed that likely played a part, I also identified another culprit: The massive amounts of caffeine he was drinking every morning. Thomas was drinking black coffee to mask underlying issues such as morning tiredness due to suboptimal sleep. Sure, the coffee was powering the early part of his day. But the side effects he was experiencing in the midafternoon were what we call a caffeine crash.

What is a caffeine crash?

Most Americans partake in some form of caffeine every day. That might include things like coffee, cacao beans, kola nuts, tea, yerba mate, sodas, and energy drinks. Some people take supplements that contain caffeine in capsules, tablets, or powders.

Regardless of its source, caffeine (in its most common, instant-release form) has nearly a 100% bioavailability when consumed orally, meaning that you absorb all of it into the bloodstream rather quickly. Its full effects kick in in about 45 to 60 minutes1 and can last three to five hours (or longer, if you're a slow caffeine metabolizer). Food can inhibit caffeine absorption, but only by a little bit. 

A few hours after drinking moderate or high doses of instant-release caffeine, many people experience a caffeine crash. Side effects vary in intensity from person to person, but include dozing off during the day, feeling irritated, and not being able to concentrate—the opposite of the desired effect people are drinking caffeine for in the first place.

For some people, a caffeine crash can also feel like you've spent the previous night bar-hopping, with side effects including gastrointestinal issues and sensitivity to light or sound.

Sustained-release caffeine2 is a relatively newer form and technology. It delivers a slower (less steep) release profile of the caffeine phytonutrient and thus, prolonged physical and cognitive energy and focus benefits (while also buffering against the aforementioned "crash").*

Why do caffeine crashes occur?

All bodies are different, and so people respond to caffeine in various ways. That explains why your friend can have two cups of coffee at dinner and still fall asleep by 10 p.m., while your morning roast might keep you wired until bedtime. To understand why caffeine crashes occur, we need to look deeper at how the body metabolizes caffeine.  

As a naturally stimulating compound, caffeine fires up the central nervous system, allowing you to become more alert and focused.* You may have more energy. An increase in adrenaline may raise your heartbeat or blood pressure slightly. For most people, these physiological changes are temporary.  

But for some people, caffeine can create undesirable effects. Mild side effects of caffeine include feelings of anxiousness, restlessness, irritability, agitation, gut upset, and subpar sleep.

Why do some people experience these things after they consume caffeine while others handle it just fine? When you consume caffeine, a liver enzyme called CYP1A2 breaks it down. The gene that codes this enzyme varies greatly among people. Scientists divide people into three groups, depending on how quickly their livers metabolize caffeine: high, regular, and low metabolizers. 

For high (aka fast) metabolizers, this enzyme breaks down and helps clear caffeine very quickly. Low metabolizers, on the other hand, break down coffee at a much slower pace, so its effects stick around much longer.

Your brain also plays a role in caffeine metabolism. The primary way caffeine increases alertness and provides energizing effects is by blocking adenosine from attaching to brain receptors.* One of adenosine's main roles is to build up during the day and slow down brain activity, making you sleepy. Once your body has metabolized that caffeine and its effects wear off, that adenosine floods brain receptors and tells your brain that it's sleepy time, even if it's in the middle of the afternoon. This can result in that dreaded caffeine crash sensation (i.e., the infamous afternoon slump).

How to eliminate a caffeine crash.

Just like most things we consume, moderation is key. Caffeine carries potentially adverse effects, depending on how much you consume as well as your personal physiology and thus, sensitivity to caffeine. If you rely on your morning coffee to pull you through the day, you might find its energizing effects tapering off midday. On the other hand, eliminating caffeine cold turkey can create some unpleasant side effects of its own. 

Consider why you rely on caffeine. Is it suboptimal sleep or stress management, or feelings of boredom or hunger? Or is it leveraging the power of this nootropic phytonutrient for cognitive energy, focus, and performance?* Investigating those underlying reasons, along with these strategies, can help eliminate a caffeine crash:


Eat a gut-supporting diet that balances blood sugar levels.

When your blood sugar levels are all over the map, many side effects of a caffeine crash get amplified. When blood sugar levels spike and crash, you may feel cranky and sleepy, which can cause you to reach for caffeine.

Eating foods (i.e., emphasize fibrous vegetables and limit refined sugars) that support your gut also helps to balance blood sugar. As a result, you will have more energy and focus, be able to maintain a healthy body composition, and bolster your immune system.


Take a focus supplement with instant- and sustained-release caffeine.

Perhaps your problem isn't caffeine intake itself, but the form of caffeine that you're consuming. Trading one (or a couple) of your daily cups of coffee for a high-quality focus supplement that promotes sustained energy can help you avoid the afternoon slump.

mbg's focus+ features both instant- and sustained-release caffeine that's 100% plant origin (from whole coffee berry and green coffee bean, respectively), so you can feel stimulating effects right away and throughout the day, minus the crash.* It's all the energy, focus, and attentiveness you want with none of unwanted side effects!*


Gradually taper off caffeine.

If you're tired of having a caffeine crash and want to quit entirely, just be aware that going off caffeine cold turkey can be a monster. Undesirable side effects kick in about 12 to 24 hours after you stop consuming caffeine. They become most pronounced within one to two days, and can last for up to a week. These include sensitivity to sounds and light, tiredness, gastrointestinal upset, mood changes, and sometimes headache.

To minimize these side effects, I taper my clients off of caffeine. Switching to half-regular and half-decaf, then gradually moving into 100% decaf over the course of three to seven days makes the weaning process more bearable. If side effects appear that are simply too much to handle, I will have the individual add back a small amount of caffeine and slowly continue the taper. The same goes for all caffeine-rich beverages, including sodas.


Set a daily caffeine cutoff time.

Poor sleep ranks high on the reasons people over-rely on caffeine and experience caffeine crashes. Not getting enough sleep can affect nearly everything, including reducing insulin sensitivity and increasing unwanted weight3. I've written about how poor quality sleep can affect gut health, and you're also more prone to suboptimal immune response4 when you don't sleep well.

The best way to avoid this issue is to set a daily cutoff point for coffee consumption. For most people, it's best to not continue drinking coffee after noon, but that's not set in stone. You should figure out what works best for you individually.

The takeaway.

Everyone metabolizes caffeine differently and consumes difference sources of caffeine. That's why people experience varying levels of caffeine crashes. It's important to listen to your body and see how caffeine affects you, as well as note if you're using caffeine to address root problems (such as lack of sleep). Once you're mindful of how your body processes caffeine, you can determine the best way to embrace caffeine in your life, while successfully mitigating caffeine crashes.

If you are pregnant, breastfeeding, or taking medications, consult with your doctor before starting a supplement routine. It is always optimal to consult with a health care provider when considering what supplements are right for you.
Vincent M. Pedre, M.D. author page.
Vincent M. Pedre, M.D.
Board-Certified Internist

Vincent M. Pedre, M.D., medical director of Pedre Integrative Health and president of Dr. Pedre Wellness, is a board-certified internist in private practice in New York City since 2004. He completed his bachelor’s degree in Biology at Cornell University before attending the University of Miami School of Medicine and completed his residency in Internal Medicine at the Mount Sinai School of Medicine. He has appeared on the Martha Stewart Show and ABC and is the author of Happy Gut: The Cleansing Program to Help You Lose Weight, Gain Energy, and Eliminate Pain. Dr. Pedre is a clinical instructor in medicine at the Mount Sinai School of Medicine and is certified in yoga and medical acupuncture.