15 Links Between Caffeine and Anxiety (Study)

Caffeine is a psychoactive drug that can cause or exacerbate anxiety and other stress-related signs and symptoms in many ways. Learn what you can do.

If you’re concerned that caffeine is making your anxiety worse, your suspicions are probably correct.

Caffeine is a central nervous system stimulant that can significantly contribute to anxiety disorders. (1)

There’s evidence that quitting caffeine can be even more beneficial for anxiety than taking prescription anti-anxiety drugs!

Here are 15 ways that caffeine is linked to anxiety.

What you’ll learn about caffeine and anxiety in this article:

• How caffeine affects stress hormones, neurotransmitters, and brain nutrients

• Why it’s easy to overdo caffeine consumption today

• Surprising reasons you may be especially sensitive to caffeine

• Four recognized caffeine-related mental disorders

• How caffeine interferes with the action of many medications, including anti-anxiety drugs

• Why green tea is the best caffeinated beverage if you have anxiety

1. Caffeine increases stress hormones.

Most people with anxiety would agree they have too much stress in their lives — and caffeine adds to the burden.

Caffeine affects the body much like stress, increasing heart rate, blood pressure, and levels of stress hormones.

Caffeine consumption can more than double your blood levels of the stress hormones cortisol and epinephrine. (2, 3)

2. Caffeine affects neurotransmitter balance.

Caffeine achieves many of its effects by blocking the activity of adenosine, a neurotransmitter that makes us tired and sleepy.

By increasing the brain chemicals dopamine and acetylcholine, caffeine gives us the feelings we desire — increased motivation, productivity, and brain power. (4, 5)

But for those with anxiety, there is a downside.

Caffeine also inhibits the calming neurotransmitter GABA. (6)

GABA puts the brakes on brain activity when needed and has been characterized as “nature’s Valium.”

It’s essential for feeling happy and relaxed, so it’s not surprising that a low GABA level is associated with anxiety and panic attacks.

Serotonin is the neurotransmitter tied closely to happiness.

The relationship between caffeine and serotonin is complex.

But there’s evidence that when consumed regularly, caffeine eventually leads to serotonin depletion. (7, 8)

3. Caffeine causes insomnia.

One of the most common side effects of both anxiety and caffeine consumption is insomnia.

In fact, caffeine-induced sleep disorder is a recognized psychiatric disorder. (9)

If anxious thoughts make you restless at night, caffeine can compound the problem.

Caffeine particularly decreases sleep stages 3 and 4 during which some of the most deep, restorative sleep takes place. (10)

Getting adequate sleep is one of the most important things you can do for brain health and mental well-being.

It’s during sleep that your brain washes away toxins and metabolic debris, repairs itself, and creates new brain cells. (11, 12, 13)

Keep in mind that caffeine hangs around in your system and that caffeine consumed even six hours before bedtime can significantly disrupt your sleep. (14)

4. You may have caffeine sensitivity.

We all know people who can drink a pot of coffee after dinner and sleep like a rock.

If you have anxiety, you probably aren’t one of them.

The difference may be in your genes.

Scientists from Harvard School of Public Health have found several genes that directly influence how your body metabolizes caffeine. (15)

You may be sensitive to caffeine because you take longer than average to metabolize it.

The average half-life of caffeine is 5-6 hours, but everyone is different and the time it can take to eliminate caffeine varies widely.

It can take as little as two to or as many as 10 hours after ingestion to metabolize half of it. (16)

And there are other reasons you may be extra sensitive to caffeine.

Caffeine sensitivity increases with age, so you might not be able to drink caffeine like you used to. (17)

Men metabolize caffeine more slowly which makes them more caffeine sensitive than most women, the exception being women who are pregnant or taking birth control pills. (18, 19)

Caffeine sensitivity can be caused by an allergic reaction to caffeine, although true caffeine allergy is extremely rare. (20)

More common is an allergy to mycotoxins, toxins produced by fungi and mold that are found in coffee. (21)

You may be taking medications that increase the side effects of caffeine.

Drinking alcoholic beverages slows down caffeine breakdown.

So do some healthy foods including grapefruit and broccoli. (22)

Impaired ability to process caffeine is not unusual in people with liver disease, especially cirrhosis. (23)

5. Caffeine may cause reactive hypoglycemia.

Hypoglycemia occurs when blood sugar drops too low.

A low blood sugar attack can leave you feeling jittery, sweating, irritable and confused, with your heart pounding — a lot like an anxiety attack.

While caffeine generally raises blood sugar levels in people with diabetes, whether caffeine truly lowers blood sugar levels in hypoglycemics is a matter under debate. (24)

If caffeine makes you feel like you are having a low blood sugar attack, you may be experiencing what’s known as relative or reactive hypoglycemia. (25, 26)

This occurs when you feel like you have low blood sugar even though your actual blood glucose level is normal.

If you suspect that your low blood sugar is exacerbated by caffeine, try going without it and notice if you have any improvement.

6. Caffeine can increase anxiety when taken with many medications.

Caffeine is so much a part of our culture, it’s easy to forget that it’s a psychoactive drug and, consequently, doesn’t always mix well with other drugs.

Drugs.com currently lists over 80 medications that should not be taken along with caffeine.

Sometimes caffeine enhances the effects of some drugs — it’s often added to over-the-counter painkillers to make them work better.

But this same property also increases the number of side effects as is the case with asthma medications, antidepressants, and some antibiotics. (27, 28)

Sometimes caffeine undermines the effectiveness of medications.

Anti-anxiety medications, sleeping pills, and lithium for bipolar disorder fall into this category.

Pharmacist Suzy Cohen reveals some alarming interactions between caffeine and prescription drugs in her book Drug Muggers: Which Medications Are Robbing Your Body of Essential Nutrients–and Natural Ways to Restore Them.

She reports that caffeine can cause tremors, panic attacks, and insomnia when taken with antidepressants that are SSRIs (selective serotonin re-uptake inhibitors).

Caffeine should be avoided when taking breathing medications that contain the stimulant xanthine.

When taken together, they can cause anxiety as well as dangerous heart palpitations, shortness of breath, and arrhythmia.

When caffeine is used with ADHD medications like Adderall and Ritalin, it increases nervousness, irritability, insomnia and heart rhythm abnormalities.

7. Added caffeine is an unregulated, synthetic chemical.

Coffee and various teas, including green tea, matcha, and yerba mate, contain caffeine naturally.

But the caffeine found in sodas, energy drinks, energy gel packs, and caffeine pills and powders is rarely extracted from tea leaves or coffee grounds — that would be prohibitively expensive.

The demand for added caffeine has far outstripped natural caffeine production since World War II.

Added caffeine is synthetically manufactured in pharmaceutical plants from chemical precursors like urea and chloroacetic acid.

It is usually made in China or sometimes in India or Germany.

Journalist and self-proclaimed caffeine addict Murray Carpenter, author of Caffeinated: How Our Daily Habit Helps, Hurts, and Hooks Us, traveled to China to check out the world’s largest caffeine plant while doing research for his book.

It was not the high-tech facility he imagined.

Here’s how he described the plant in his book: “… half the windows were smashed, and rags streamed out. Bags of stockpiled chemicals sat inside the broken first-floor windows. The place reeked — a chemical stench to make you gag — and a tall rusty tank leaked a tarry sludge.”

He reveals that if you drink soda or energy drinks, you’ve almost certainly consumed caffeine produced there.

Lastly, don’t be impressed if you see the words “naturally caffeinated” on a product label.

Unscrupulous manufacturers ignore labeling requirements and use the synthetic version anyway. (29)

Natural and synthetic caffeine are technically identical, yet can be told apart by carbon dating. (30)

Synthetic caffeine registers as “older” since it’s made from fossil fuels.

Oddly, synthetic caffeine can exhibit another telltale sign — sometimes it glows. (31)

8. Caffeine is linked to psychiatric disorders.

It’s been recognized for decades that the symptoms of too much caffeine are very similar to those of many psychiatric disorders.

Enough caffeine can even create symptoms of anxiety in a healthy person that are indistinguishable from those experienced by anxiety disorder sufferers.

Some psychiatrists recommend that routine psychiatric assessments should include examining caffeine consumption since removing caffeine can be more beneficial than prescribing an anti-anxiety drug.

Caffeine use has been linked to mental disorders of all kinds including anxiety, panic, depression, as well as sleep and eating disorders.

Taking schizophrenic patients off caffeine has improved their anxiety, irritability, and hostility. (32)

Going back as far as 1987, it’s been recommended that decaffeinated beverages should be provided on psychiatric wards.

9. Caffeine causes at least four recognized mental disorders.

The Diagnostic and Statistical Manual of Mental Disorders (DSM) is the American Psychiatric Association’s standard guide of mental disorders.

The most recent edition is the fifth version known as the DSM-5.

The DSM-5 now lists four caffeine-related disorders: (33)

• caffeine intoxication

• caffeine-induced anxiety disorder

• caffeine-induced sleep disorder

• caffeine withdrawal

The World Health Organization and many health care professionals recognize caffeine addiction as a clinical disorder.

For now, the preferred term is caffeine use disorder. (34)

It’s been included as a condition for further study in the DSM-5.

10. It’s easier than ever to overdo caffeine consumption.

There are more sources of caffeine than ever before.

You expect to find it in coffee, tea, chocolate, and cola soda, but it’s also hidden in prescription drugs, over-the-counter painkillers, non-cola drinks, vitamin waters, brain tonics, and even in vitamins and herbal supplements. (35)

The amount of caffeine in energy drinks can be deceiving since some of the serving sizes of these drinks are so small.

5-Hour Energy Shot contains a jaw-dropping 100 mg of caffeine per ounce.

Another problem is that labels aren’t always accurate.

Sunkist orange soda lists 41 mg of caffeine on its label, but in fact was found to have almost six times as much caffeine at 240 mg per bottle. (36)

Caffeine’s effects are consistently underestimated, but here’s what escalating amounts of caffeine can do: (37)

• 1/64 teaspoon will give you a subtle boost

• 1/16 teaspoon (the amount in 12 oz of coffee) can lead to addiction

• 1/4 teaspoon causes acute anxiety

• 1 tablespoon is enough to kill an adult

It’s thought to be virtually impossible to drink yourself to death with naturally occurring caffeine.

But now pure caffeine pills and powder can easily and inexpensively be purchased online, making caffeine overdose a reality.

Sadly, there have been a few deaths caused by caffeine powder overdose. (38, 39)

11. Caffeine robs your brain of essential nutrients.

Caffeine causes nutrients to be excreted from your body, some of which are particularly important for your brain health and mood.

One of the nutrients that gets depleted is magnesium, a mineral that has profound effects on your mental well-being. (40)

Magnesium plays a critical role in a number of brain-related disorders including anxiety, depression, addictions, ADHD, bipolar disorder, schizophrenia, and Alzheimer’s disease. (41, 42, 43, 44, 45)

Dr. Carolyn Dean, author of a bestselling book on magnesium, states emphatically that “Hands down, bar none and without a doubt, the top supplement for anxiety is magnesium and in my experience, if it doesn’t work that means you haven’t taken enough.” (46)

Caffeine also robs you of the B complex vitamins, the “anti-stress vitamins.”

Anxiety is a common sign of B vitamin deficiency. (47)

Taking extra B vitamins can address imbalances of the brain chemicals GABA, serotonin, dopamine, and epinephrine that contribute to anxiety. (48)

12. Caffeine might make your brain supplement useless.

When you are anxious, blood flow to the brain is already reduced and caffeine can reduce it further. (49)

Caffeine restricts blood flow to the brain by as much as 27%. (50)

Blood flow is the delivery system for getting nutrients of all kinds to your brain including oxygen, water, glucose, vitamins, and minerals.

Many people take brain supplements and nootropics like ginkgo, citicoline, curcumin, and vinpocetine to increase blood flow to the brain not realizing that the caffeine they drink could be rendering them useless.

13. Women experience hormone-related sensitivity to caffeine.

Caffeine’s effects vary depending on how quickly you process it.

If you are pregnant or taking birth control pills it can take longer to process caffeine than usual, up to twice the usual half-life of four to five hours. (51, 52)

This means you’ll get double the boost and the side effects from any caffeine you consume.

Caffeine also increases symptoms of menopause including anxiety, insomnia, hot flashes, bone loss (by leaching calcium), heart palpitations, and mood swings. (53)

Likewise, caffeine can also worsen the anxiety, fatigue, and irritability experienced by women with premenstrual syndrome (PMS). (54)

14. Caffeine induces “panic attacks on demand” for scientific research.

It’s notoriously difficult to study panic attacks since you can’t get study subjects to experience them on demand.

Or can you?

Caffeine so reliably induces panic attacks that it’s used for that purpose in studies.

By giving participants with social anxiety disorder 480 mg of caffeine, 61% of them experienced caffeine-induced panic attacks. (55)

Researchers have also used caffeine to induce auditory hallucinations (i.e., hearing things) in test subjects. (56)

15. Caffeine withdrawal causes anxiety.

If you have anxiety, caffeine gets you coming and going.

Not only does it make you feel anxious when you drink it, it also makes you anxious when you quitdrinking it!

Caffeine withdrawal is a recognized mental disorder. (57)

Withdrawal symptoms include anxiety as well as brain fog, depression, irritability, fatigue, insomnia, muscle aches, and nausea.

Fortunately, the worst of caffeine withdrawal usually lasts only a few days.

If you’ve decided that eliminating caffeine would be a good idea, learn how to quit caffeine with minimal side effects in our article on caffeine addiction and withdrawal.

The Best Caffeinated Drink If You Have Anxiety: Yerba Mate, Ginseng, Moral Root or simple Green Tea (just make sure its organic)

Not all sources of caffeine are equally beneficial or detrimental.

Soft drinks contain synthetic caffeine, loads of sugar, and have no nutritive value.

Energy drinks are no better even though they may contain some added herbs or vitamins.

The International Society of Sports Nutrition has concluded that any performance enhancement from energy drinks comes from caffeine and sugar, NOT from these added nutrients. (58)

Traditional caffeinated drinks like coffee, tea, and yerba mate contain antioxidants, vitamins, minerals, amino acids, and phytonutrients that offer major health benefits and actually build a better, healthier brain.

If you’d like to continue to drink some caffeine to stay alert and productive, there’s no better drink than green tea.

Green tea will help you stay simultaneously calm and focused due to two unique compounds, EGCG and l-theanine.

EGCG (epigallocatechin gallate) is a potent antioxidant that can improve your mood and make you more resilient to stress by increasing the calming neurotransmitter GABA. (59, 60, 61)

One study found EGCG to be as effective at relieving anxiety as the anti-anxiety medication benzodiazepine! (62, 63)

L-theanine is a relaxing amino acid that causes an increase in alpha brainwave activity, putting you in a state similar to that experienced during meditation. (64)

The caffeine, EGCG, and theanine in green tea work together to induce the desirable state of calm alertness. (65)

Caffeine and Anxiety: The Bottom Line

Caffeine is not the innocuous substance it might seem to be.

The evidence is overwhelming that this psychoactive drug can exacerbate or cause anxiety.

It’s been linked to a handful of recognized psychiatric disorders.

Caffeine causes anxiety by many mechanisms — increasing stress hormones, reducing calming neurotransmitters, depleting nutrients, and reducing blood flow to the brain.

If you’re going to drink any caffeinated drink, make it green tea which contains relaxing compounds.