Caffeine is the world’s most popular stimulant. The psychoactive effects of caffeine provide a kick of energy for roughly 93 percent of Americans. It’s estimated that nearly 25 percent of coffee drinkers consume caffeine three or more times daily.
Caffeine consumption isn’t just socially acceptable; it’s practically mandatory for many people. College students and graduates owe much of their success to caffeine-fueled study sessions. The same is also true in several professions. Journalists, police officers, and teachers top the list of workers who consume the most caffeine.
Not all of caffeine’s effects are harmful. For example, caffeine has been shown to positively support brain function. The tricky thing about caffeine is that too much can have the opposite effect.
This article dives into what caffeine is and how it can affect the brain over time.
What Is Caffeine?
Humans have been consuming caffeine for a very long time. We can confidently trace caffeine consumption as far back as 1000 B.C. During this time, the people of modern-day China started to regularly brew and consume tea.
Tea and other caffeinated beverages like coffee would eventually spread worldwide. While these drinks were used medicinally and recreationally, there was still a lot that remained unknown about caffeine. That changed in 1819 when Friedlieb Ferdinand Runge analyzed a box of Arabian mocha beans. The young physician isolated and purified the white crystalline substance that we call caffeine.
It’s now known that caffeine is naturally found in the leaves and fruits of more than 60 different plants. The most commonly known are coffee beans, tea leaves, kola nuts, and cacao pods. These plants are crucial ingredients in coffee, tea, soft drinks, and chocolate products.
Neuroscience-related studies have concluded that caffeine acts as a short-term central nervous system stimulant, and it’s been labeled as such by government entities like the Food and Drug Administration. In many ways, the effects of caffeine are similar to the effects of sugar on your brain. However, the psychoactive effects of caffeine are typically much stronger than sugar.
How Does Caffeine Affect Your Brain?
If you’ve ever had a cup of coffee, you know that caffeine significantly affects your central nervous system. As a stimulant, it can help you to feel more alert and energetic. You’ll typically feel less tired and more focused once the caffeine hits your bloodstream.
There are two primary reasons why you feel these effects:
Caffeine Blocks Adenosine Receptors
Caffeine blocks adenosine receptors in your brain. Adenosine serves many purposes in your body, but one of the primary ones is to slow down neuron activity. By doing so, the body and brain can wind down enough so that you can fall asleep and stay asleep throughout the night.
Adenosine is released by the basal forebrain whenever you use energy. The adenosine then travels around your body via the bloodstream and slowly builds up throughout the day. At a certain point, you’ll have accumulated enough adenosine to start feeling sleepy. While you’re sleeping, the adenosine is broken down and dispersed so that the cycle can begin again the following day.
It’s important to note that caffeine doesn’t affect the amount of adenosine in your body — just the adenosine’s ability to bind to receptors and induce those feelings of tiredness and sleepiness. In other words, caffeine merely inhibits your ability to perceive the effects of adenosine.
With that, having a cup of coffee after a long day can reduce your feelings of sleepiness, but when the caffeine wears off and the receptors are available for binding, all of that built-up adenosine floods receptors, resulting in the infamous caffeine crash.
Caffeine Increases Neurotransmitter Release
The other reason caffeine provides an energetic kick is that it increases the release of neurotransmitters in your brain. The inhibitory control of acetylcholine in the hippocampus and prefrontal cortex is removed, which floods your brain with neural activity.
One of the neurotransmitters being released is dopamine, known as the “feel good” hormone. It’s one of the reasons why eating chocolate or drinking a hot cup of coffee usually puts you in a better mood.
Dopamine might make you feel good, but it doesn’t give you the signature jolt of energy associated with caffeine. The “pick-me-up” that you get from caffeine is largely the result of caffeine’s effects on cortisol and adrenaline.
These are two of your “adrenal hormones” produced at the top of your kidneys. Along with the other adrenal hormones, cortisol and adrenaline play important roles in several essential bodily functions.
The most important of these functions occurs during times of great stress. These neurotransmitters can give your brain and body an enormous energy boost, with the intention of helping you handle an emergency (i.e. perceived threat) as best as possible.
The excessive flow of energy throughout your body makes the “fight or flight response” possible during stressful situations.
How Much Caffeine Is Too Much Caffeine?
The effects listed above make it clear why caffeine is so popular. Feeling less tired and experiencing a boost of energy can be extremely beneficial for coffee drinkers. The tricky thing about caffeine is that it’s easy to get addicted to these effects. You may want to be careful with your daily caffeine consumption to avoid becoming dependent.
A few factors, such as your weight, general health, and metabolism rate could influence the amount of caffeine you can handle daily. However, experts recommend limiting caffeine consumption to around 400 milligrams or less daily. If you frequently consume more than that, you may be at high risk for developing a physical or psychological caffeine dependence.
Developing a dependency on caffeine will naturally result in building up a tolerance to it, too. It’s the same as any other drug: the more you have of it, the less effective it may be over time.
As you start to increase your caffeine consumption to compensate for this tolerance, you can develop some of the following symptoms:
- Elevated heart rate and blood pressure
- Abnormal heartbeat
- Acid reflux and heartburn
- Insomnia, sleeplessness, and low-quality sleep
- Anxiety, nervousness, and feeling “on edge”
- Shaking hands and muscle tremors
- Frequent urination and diuresis which can cause dehydration
- Nausea, vomiting, and diarrhea
- Headaches, migraines, and dizziness
- Confusion, rambling speech, and hallucinations
In some extreme cases, higher doses of caffeine can cause cardiac arrest or coma. It can be a good idea to meet with a doctor if you drink a lot of caffeine and experience some of the symptoms listed above.
You might have a caffeine addiction which can be fairly difficult to treat without help. Typically, the effects of caffeine withdrawal take place 12 to 24 hours after you last consumed caffeine and can last for a week or longer.
These are a few symptoms that commonly occur during caffeine withdrawal:
- Fatigue, lethargy, and drowsiness
- Mood swings, irritability, depression, and anxiety
- Inability to focus, confusion, and slow reaction times
- Reduced memory recall
- Flu-like symptoms such as sweating, nausea, and vomiting
- Muscle pain and stiffness
What Foods Have the Most Caffeine?
Caffeine addiction is nothing to take lightly. The withdrawal symptoms might not be lethal, but they can surely make life difficult. Just because caffeine is legal doesn’t necessarily mean that it can’t be dangerous. If you want to avoid developing a dependency, it can be helpful to keep a closer eye on the things you eat and drink each day.
Here is a list of the foods that have the most caffeine and a rough estimate of how much is in each standard serving:
- Drip coffee: 150 to 240 milligrams per cup
- Instant coffee: 80 to 120 milligrams per cup
- Espresso coffee: 105 to 110 milligrams per cup
- Decaf coffee: 2 to 6 milligrams per cup
- Black tea: 65 to 105 milligrams per cup
- Green tea: 30 to 50 milligrams per cup
- Soft cola drinks: 60 to 75 milligrams per 12-ounce can
- Energy drinks: 120 to 240 milligrams per 12-ounce can
- Hot chocolate: 5 to 10 milligrams per cup
- Chocolate milk: 2 to 5 milligrams per cup
- Chocolate pudding: 3 to 8 milligrams per cup
- Chocolate ice cream: 3 to 6 milligrams per cup
- Milk chocolate bar: 10 milligrams per 50 grams
- Milk chocolate chips: 30 to 40 milligrams per cup
- Dark chocolate bar: 40 to 50 milligrams per 50 grams
- Certain pain relievers: 25 to 70 milligrams per capsule
Keep Your Mind Sharp by Limiting Your Caffeine Consumption
In a lot of ways, caffeine is what makes the world go around. Many people rely on a frequent dose of caffeine to get through the day, whether through regular cups of coffee or energy drinks. Much of the world is likely addicted to caffeine and might not even realize it. If you want to avoid developing an addiction, you might want to start limiting your daily basis of caffeine use.
The good news is that you can get a jolt of energy from non-caffeinated sources. For example, protein can provide you with a ton of energy. It won’t be the same as chugging caffeine, but it can be an excellent substitute that’s much more healthy.
Caffeine can be very difficult to avoid. Especially if you’re a big fan of chocolate in all its forms. No one is saying that you should eliminate caffeine from your diet. However, keeping an eye on your caffeine intake is probably a good idea. It’s easy to become addicted to caffeine and develop a tolerance.
Overindulging in caffeine can have some rough side effects on your cognitive performance. It’s best to curb the habit sooner rather than later, as caffeine addiction can be hard to get through.
If you’re looking to knock down your caffeine intake a few levels, consider making lifestyle changes that might lower your need for caffeine. Getting more exercise, improving your diet, meditating, sleeping, and playing brain games can help to keep your mind sharp, and a sharper mind might not have as much of a need for caffeine throughout the day!
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Author Michael Pollan discusses how caffeine changed the world | Harvard Gazette
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19 Horrible Things That Can Happen if You Drink Too Much Caffeine | INC
Spilling the Beans: How Much Caffeine is Too Much? | FDA
Adrenal Hormones | Endocrine Society
Energy Drinks and the Neurophysiological Impact of Caffeine | Frontiers
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Adenosine and Sleep | Sleep Foundation
Arousal Effect of Caffeine Depends on Adenosine A2A Receptors in the Shell of the Nucleus Accumbens | Journal of Neuroscience