Anxiety after coffee?
Here's why caffeine can trigger anxiety, what caffeine does inside the body, and why some people are far more sensitive to it than others.
Here's why caffeine can trigger anxiety, what caffeine does inside the body, and why some people are far more sensitive to it than others.
Within 15 to 45 minutes of drinking a cup of coffee, caffeine travels through the bloodstream and reaches the brain. There, it blocks adenosine receptors, the neural “brakes” that help promote calm and drowsiness.
This blockade leads to the release of dopamine and norepinephrine: two neurotransmitters that drive “heightened alertness, increased arousal, and reduced fatigue,” says Dr. Amin Yehya, a cardiologist at Sentara Health in Virginia.
But in higher amounts, dopamine and norepinephrine also raise heart rate and blood pressure and activate brain regions involved in threat perception. It’s the same system that drives the body’s stress response and can contribute to restlessness and a racing mind.
Caffeine can also trigger anxiety through another pathway. It activates the hypothalamic-pituitary-adrenal (HPA) axis, increasing cortisol and adrenaline, which are the body’s core stress hormones. “Caffeine stimulates the same hormonal pathways that activate during stress,” Yehya says.
Not everyone feels anxious after drinking coffee, and genetics play a role in determining who does. Variations in genes alter how the brain’s adenosine and dopamine receptors function, Yehya says, while certain mutations can slow caffeine metabolism in the liver.
People with these gene variants process caffeine more slowly, allowing it to linger in the bloodstream and prolonging its stimulating effects, which can contribute to feeling more anxiety.
This is why “the same cup of coffee can feel totally different from one person to another,” Higgins says.
The U.S. Food and Drug Administration recommends no more than 400 mg of caffeine per day—about two to three 12-oz. cups of brewed coffee—for most healthy adults. But that limit isn’t hard and fast. “There is no designated amount of caffeine that universally triggers anxiety,” Yehya says.
Genes aren’t the only factor. So are a person’s caffeine tolerance and underlying health, says Dr. Ajay Pillai, an electrophysiologist at VCU Health Pauley Heart Center. “Caffeine intake may acutely raise heart rate and blood pressure by as much as 5 to 10 mmHg,” he says. “This effect may be more pronounced in people with hypertension or those already under stress.”
Sleep deprivation, chronic stress, and hormonal fluctuations can all amplify caffeine’s effects. “When the body is already under stress, caffeine can compound that response,” says Dr. Sogol Ash, a functional and preventative medicine doctor and medical advisor to the vitamin patch company, Barrière. “Poor sleep, hormonal fluctuations, and anxiety elevate baseline levels of cortisol and adrenaline, leaving the nervous system in a heightened state.”
Add in caffeine, and the effects can feel stronger.A lack of sleep fundamentally changes how caffeine interacts with the brain.
“When you're running on empty, your prefrontal cortex is already compromised,” Woods says. “Caffeine creates the illusion of alertness without restoring actual cognitive function. You might feel awake, but your ability to concentrate remains impaired.” Women taking hormonal contraceptives or who are pregnant may also metabolize caffeine more slowly.
If you experience anxiety, palpitations, or insomnia with moderate coffee consumption, it might be time to re-evaluate your caffeine habit. “If someone’s anxiety persists despite changes in caffeine intake—or their symptoms impair daily functioning—other medical conditions should be considered,” Yehya says. That could include anxiety disorders, cardiac arrhythmias, or thyroid issues.
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