by Health By Principle

Your Body on Anxiety


Maybe you are about to take an important test, or supposed to speak in front of a large gathering, or get onto an airplane… and there it is: Your ice-cold hands shake slightly, while your palms are getting sweaty and slippery. Your chest tightens, and it feels as if your heart is thumping so loudly that everyone can hear it. There is a loud buzzing in your ears. Your mouth becomes drier and drier. You feel an intensifying knot in your stomach, making you wonder whether you are going to lose your lunch within a matter of minutes.

To a certain degree, anxiety is a normal part of life. When you are faced with difficult challenges, it can propel you to better performance; however, too much anxiety, and it can turn into a crippling disorder.

Worldwide, about 264 million people suffer from some kind of anxiety disorder that negatively affects their everyday life. In the United States, 31.1 percent of adults will at some point in their life experience an anxiety disorder—such as generalized anxiety, a phobia (fear of flying, dogs, public speaking and so on), or obsessive-compulsive disorder, among others.[1]

The problem is so pervasive that new drugs seem to appear on pharmacists’ counters and drugstore shelves with great regularity. There exist research centers exclusively devoted to its study, like the Center for Anxiety and Related Disorders at Boston University.[2]

Clearly, as a mental health issue, anxiety disorders have a major psychological component—but what about the underlying physiology?

In other words, what happens in your body while you are experiencing an anxiety attack?

It Is Fight-or-Flight Time

When you feel anxious and stressed, different parts of your brain set in motion a hormonal chain reaction:

  • Your amygdala—an almond-shaped part of the brain where your emotional memories and learned reactions are stored—activates the so-called HPA axis (hypothalamic-pituitary-adrenal axis).
  • Your hypothalamus—a small structure right above the brain stem, which is responsible for the regulation of your autonomic nervous system—releases a hormone called corticotropin-releasing factor (CRF).
  • CRF “switches on” the pituitary gland, which consists of a pea-sized knob at the bottom of the hypothalamus.
  • The pituitary gland then releases the adrenocorticotropin hormone (ACTH). Your bloodstream transports ACTH to your kidneys, where it causes the adrenal gland to release the stress hormones: adrenaline and cortisol.

Noradrenaline is another important stress hormone and neurotransmitter; it is produced directly in the brain, in a part of the brain stem called the locus ceruleus. Other neurotransmitters that may modify your body’s reaction include gamma-aminobutyric acid (GABA). GABA is inhibitory: it helps your brain to filter out stimuli that are not threatening and reduces stress hormone production.

You Feel Your Heart Beating Quickly

Adrenaline, noradrenaline and cortisol all prepare your body for an emergency response. As the human body evolved over time, it developed a fight-or-flight response to deal with threats in the form of wild animal attacks or encounters with enemy tribes.

Nowadays, threats to our well-being may come in the form of an argument with your spouse, a looming lay-off from your job, a terrorist event, and so on. Still, the biological mechanisms have remained the same:

  • Your blood sugar increases, so that your muscles have more fuel available to either fight or run.
  • Your breathing becomes faster and deeper, transporting more oxygen to your blood. This is why your chest feels tighter.
  • Your blood vessels constrict and direct blood away from your hands and feet towards your skeletal muscles, preparing your body to fight or flee. This is why your hands and feet turn cold and your skin looks pale.
  • Your blood pressure increases. This is why you may have a buzzing or ringing in your ears.
  • Your pupils dilate, allowing your eyes to take in more information.
  • Your digestive processes stop as blood is directed away from your digestive organs (mouth, stomach, bowel). Your saliva production decreases drastically. This is why your mouth becomes dry and why you may feel the need to use the restroom or even vomit.

If you have an anxiety disorder, you will probably have experienced a downward spiral. You know that you are going to encounter a situation likely to cause an anxiety attack with all the symptoms above, and so the anticipation already provokes a great deal of anxiety.

Unfortunately, as with any physical illness, a mental health issue cannot be cured by simply explaining to the sufferer the underlying physiological mechanisms. This is especially because anxiety also has a genetic component: some people have decreased levels of GABA and hence constantly elevated stress hormone levels. But understanding why your body on anxiety feels and reacts in a certain way may help you to cope much better with the symptoms…






- Anxiety and Depression Association of America,

- David Barlow, Anxiety and its Disorders: The Nature and Treatment of Anxiety and Panic, second edition (The Guilford Press, 2004).

- Linda Geddes, “Why We Worry: Understanding Anxiety and How to Help It,” New Scientist,

- Scott Stossel, My Age of Anxiety: Fear, Hope, Dread, and the Search for Peace of Mind (Vintage, 2013).


[1] For these statistics, see

[2] On the Center of Anxiety and Related Disorders (CARD) at Boston University, see



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