Anxiety has a bad reputation. It keeps people awake, makes hearts race and turns ordinary days into hard work. Yet anxiety exists for a reason. It is one of the oldest protective systems we have, and understanding what it is for is often the first step towards living with it more peacefully.
In this article I want to explain what anxiety does, why it can fire too often, and something that is easy to overlook: sometimes the body itself produces sensations that feel exactly like anxiety. If you are mainly struggling with sudden attacks of fear, you may also want to read Panic attacks: the vicious circle and how to step out of it.
What anxiety is for
From an evolutionary point of view, anxiety prepares us to detect and deal with threats. It tends to become more sensitive when danger is more likely, or when we are more vulnerable to it. Someone walking alone at night, starting a new job or waiting for medical results is more alert for good reasons.
The system is often compared to a smoke detector. A smoke detector that sometimes goes off when you burn the toast is annoying, but one that stays silent during a real fire would be far worse. Our alarm system is set the same way: it accepts many false alarms so that it rarely misses a real danger. This explains why anxiety so often feels out of proportion. It was built to err on the side of caution.
Researchers also separate fear from anxiety. Fear is a fast, short response to a clear threat in front of you. Anxiety is a longer, more diffuse state of being on guard for something that might happen (Davis et al., 2010). Both use the same alarm system.
What anxiety does in the body
When the alarm switches on, the body gets ready to fight or flee. Your heart beats faster, breathing quickens, muscles tense, digestion slows and attention narrows on possible danger. You may notice:
- a fast or pounding heartbeat
- tight chest, shoulders or jaw
- sweating, trembling, hot or cold waves
- a churning stomach or the need to go to the toilet
- dizziness or tingling
- restlessness, irritability and difficulty sleeping
- racing thoughts and a constant “what if”
Each of these has a purpose in a real emergency. In a meeting, on a bus or in bed at night, they feel like the body has turned against you.
When the alarm fires too often
Anxiety becomes a problem when the alarm goes off too strongly, too often, or in situations that are not dangerous, and when it starts shaping your life. Anxiety disorders are the most common group of mental health conditions: across studies, up to a third of people meet the criteria at some point in their lives (Bandelow & Michaelis, 2015). That includes generalised anxiety, panic disorder, social anxiety and specific phobias.
Many things can turn up the sensitivity of the system: stress that has lasted a long time, difficult early experiences, illness, loneliness, big life changes, or simply a temperament that has always been more watchful. None of these is a personal failure. They are reasons why the threshold sits lower for some people than for others.
When the cause may be physical
This is the part that is often forgotten. Not every racing heart, trembling hand or wave of dread starts in the mind. Several physical conditions and substances can produce sensations that feel very much like anxiety, and guidelines recommend checking for them before an anxiety disorder is diagnosed (Bandelow et al., 2014). Some examples:
- An overactive thyroid (hyperthyroidism). Too much thyroid hormone speeds up the body: palpitations, sweating, trembling, weight loss, restlessness and poor sleep. In a large Danish register study, people with hyperthyroidism were more often treated with anti-anxiety medication, both before and after their diagnosis (Brandt et al., 2014).
- Heart rhythm problems. Conditions such as atrial fibrillation can cause palpitations and breathlessness, and anxiety and depression are common in people who have them (Patel et al., 2013).
- Caffeine and other stimulants. A meta-analysis found that higher caffeine intake was linked to more anxiety in general (Liu et al., 2024). Energy drinks, some diet pills and decongestants can have similar effects.
- Low blood sugar, anaemia, asthma and other breathing problems. All of these can cause shakiness, a fast heart or a feeling of not getting enough air.
- Medications and withdrawal. Some medicines list restlessness or anxiety as side effects, and stopping alcohol, sleeping pills or certain antidepressants abruptly can cause strong anxiety-like symptoms.
Worth knowing
If your anxiety appeared suddenly, without an obvious reason, or comes with symptoms such as weight loss, a very fast resting heart rate, heat intolerance or fainting, it is worth seeing a doctor. A basic check-up, often with a few blood tests, can rule out many physical causes.
Body and mind also influence each other in both directions. A physical condition can cause anxiety, and anxiety can make physical symptoms feel stronger. Finding a physical cause does not mean your feelings were “not real”, and finding none does not mean you are imagining things. Both answers are useful, because they point to the right kind of help.
What helps
Getting to know your alarm
Many people feel some relief when they understand that anxiety follows a pattern: alarm on, body preparing, mind looking for danger. Naming it (“this is my alarm system”) creates a little distance between you and the feeling.
Treating anything physical
If a doctor finds a physical cause, treating it often reduces the anxiety too. Cutting down on caffeine, adjusting a medication with your doctor or treating a thyroid problem can make a noticeable difference.
Lowering the background level
Sleep, regular meals, movement, time outdoors and time with people you trust lower the overall level of tension. None of these is a treatment on its own, and all of them make other tools easier to use.
Facing instead of avoiding
Avoidance brings relief in the moment and keeps anxiety alive over time, because the alarm never learns that the situation is safe. Cognitive behavioural therapy works on exactly this. A meta-analysis of 69 randomised trials found that its benefits for several anxiety disorders were still present up to a year after treatment ended (van Dis et al., 2020), and internet-delivered versions have also been shown to help adults with anxiety and low mood (Arnberg et al., 2014).
When to look for support
It may be time to talk to someone if anxiety takes up a large part of your day, if you avoid places or activities, or if your body and your worries keep feeding each other. You can also read about how anxiety sometimes turns on itself in Fear of fear: when anxiety feeds itself.
If you have chest pain, trouble breathing, fainting or symptoms you have never had before, please seek medical help straight away. If you are in crisis or having thoughts of ending your life, call your local emergency number (for example 112 in Europe or 911 in North America and Mexico), or find a free, confidential helpline in your country at findahelpline.com.
More about therapy with me.
References
- Arnberg, F. K., Linton, S. J., Hultcrantz, M., Heintz, E., & Jonsson, U. (2014). Internet-delivered psychological treatments for mood and anxiety disorders: a systematic review of their efficacy, safety, and cost-effectiveness. Plos One, 9(5), e98118. https://doi.org/10.1371/journal.pone.0098118
- Bandelow, B., & Michaelis, S. (2015). Epidemiology of anxiety disorders in the 21st century. Dialogues in Clinical Neuroscience, 17(3), 327–335. https://doi.org/10.31887/dcns.2015.17.3/bbandelow
- Bandelow, B., Lichte, T., Rudolf, S., Wiltink, J., & Beutel, M. E. (2014). The diagnosis of and treatment recommendations for anxiety disorders. Deutsches Arzteblatt International, 111(27-28), 473–480. https://doi.org/10.3238/arztebl.2014.0473
- Brandt, F., Thvilum, M., Almind, D., Christensen, K., Green, A., Hegedüs, L., & Brix, T. H. (2014). Hyperthyroidism and psychiatric morbidity: Evidence from a Danish nationwide register study. European Journal of Endocrinology, 170(2), 341–348. https://doi.org/10.1530/eje-13-0708
- Davis, M., Walker, D. L., Miles, L., & Grillon, C. (2010). Phasic vs sustained fear in rats and humans: Role of the extended amygdala in fear vs anxiety. Neuropsychopharmacology, 35(1), 105–135. https://doi.org/10.1038/npp.2009.109
- Liu, C., Wang, L., Zhang, C., Hu, Z., Tang, J., Xue, J., & Lu, W. (2024). Caffeine intake and anxiety: A meta-analysis. Frontiers in Psychology, 15, 1270246. https://doi.org/10.3389/fpsyg.2024.1270246
- Patel, D., Mc Conkey, N. D., Sohaney, R., Mc Neil, A., Jedrzejczyk, A., & Armaganijan, L. (2013). A systematic review of depression and anxiety in patients with atrial fibrillation: The mind-heart link. Cardiovascular Psychiatry and Neurology, 2013, 159850. https://doi.org/10.1155/2013/159850
- van Dis, E. A. M., van Veen, S. C., Hagenaars, M. A., Batelaan, N. M., Bockting, C. L. H., van den Heuvel, R. M., Cuijpers, P., & Engelhard, I. M. (2020). Long-term outcomes of cognitive behavioral therapy for anxiety-related disorders: A systematic review and meta-analysis. JAMA Psychiatry, 77(3), 265–273. https://doi.org/10.1001/jamapsychiatry.2019.3986
This article is exploratory and meant for information and reflection. It cannot capture the full complexity of any individual situation, and your own experience may be different. It does not replace a diagnosis or treatment.
