How Stress Affects Your Body: A Simple Guide

Stress is one of those things we all talk about, but few of us actually understand what it is doing to our internal systems. We tend to treat it as a mental hurdle or a busy schedule, but the reality is that stress is a full body event. It is a biological survival mechanism that, when left running in the background for too long, starts to wear out the machinery.

As we head into Stress Awareness Month, it is time to look under the hood. If you have been feeling tired but wired, struggling to sleep, or catching every cold that goes around, your nervous system might be stuck in a loop. Understanding how this works is the first step toward actually managing it.

What does stress actually do to your system?

Your body does not distinguish between a physical threat and a demanding work deadline. When your brain perceives a stressor, it kicks off a two-part response designed to keep you alive.

The first part is the rapid response, often called the fight or flight mode. This involves the Sympathetic Adrenomedullary axis, which sounds complex but is essentially your body’s emergency broadcast system. It floods your system with adrenaline and noradrenaline. Your heart rate jumps, your breath quickens, and your body redirects blood flow away from “non-essential” tasks like digestion and toward your muscles.

The second part is a bit slower, peaking about 20 to 30 minutes later. This is the Hypothalamic-Pituitary-Adrenal (HPA) axis. It releases cortisol, often called the primary stress hormone. Cortisol is a metabolic regulator. Its job is to keep your energy levels high by mobilising glucose so you can stay in the fight. In short bursts, this system is brilliant. It helps you focus and react. The problem starts when the “off” switch gets stuck.

What happens when you are stressed for a long time?

In the world of research, we call the cumulative wear and tear on the body allostatic load. Think of it like a car engine. You can redline it for a short sprint, but if you drive from Auckland to Wellington at the redline, the engine is going to fail.

When stress becomes chronic, your cortisol levels never quite return to baseline. This creates a few specific problems for your health.

Your heart takes the hit

Chronic stress is a major driver of cardiovascular issues. Constant sympathetic activity keeps your blood pressure elevated, which can lead to pathological remodelling of the heart, such as an increased left ventricular mass. It also causes inflammation in your arteries, promoting the development of plaque and increasing the risk of heart disease. Studies have shown that workplace stress, particularly when you have high demands but low control, is a significant predictor of heart issues.

Your immune system slows down

While a short burst of stress can actually boost your immunity, chronic stress does the opposite. Prolonged exposure to cortisol eventually suppresses your immune response. It reduces the effectiveness of your white blood cells, making you more susceptible to infections and even slowing down how quickly your body heals from minor wounds.

Your brain feels the fog

Your brain is the master regulator of the stress response, but it is also highly sensitive to it. Chronic stress can actually lead to physical changes in the brain. It can cause atrophy in the hippocampus, the area responsible for memory, and the prefrontal cortex, which handles decision-making. At the same time, it can cause the amygdala, your brain’s fear centre, to become hyper-responsive. This is why you feel scattered, forgetful, and constantly anxious when you are under pressure.

What actually helps with stress?

The good news is that none of this is permanent. Your system is designed to be resilient, but you have to give it the right tools to reset. We focus on four fundamental pillars for managing the load.

Why exercise is a natural stress-reliever

Exercise is one of the most effective ways to flush stress hormones out of your system. It is not just about fitness; it is about chemistry. Physical activity increases levels of feel-good chemicals like dopamine and serotonin while lowering adrenaline. It also improves your heart rate variability, which is a key marker of a healthy, balanced nervous system. You do not need to run a marathon. A brisk 20-minute walk in a green space can be enough to signal to your body that the threat has passed.

The power of talking to people you trust

Humans are wired for connection. When we spend time with people we trust, our bodies release hormones that create a sense of calm and safety. Social support acts as a buffer. It literally tells your nervous system to drop its guard. Whether it is a quick coffee with a mate or a walk with whānau, prioritising these interactions is a vital part of your health strategy.

How to use your breath to calm your brain

If you want to manually override your stress response, use your breath. Techniques like diaphragmatic breathing (belly breathing) or box breathing are used by everyone from athletes to the military to stay calm under pressure. By slowing your breath to about six cycles per minute, you stimulate the vagus nerve. This sends a direct signal to your brain to activate the parasympathetic nervous system, the branch responsible for “rest and digest.”

Why saying no is essential for your health

This is the most overlooked part of stress management. If your stress comes from an overloaded schedule or constant boundary crossings, no amount of yoga will fix the root cause. Setting clear boundaries is a value-based act of self-care. It protects your time and energy so you can actually recover. Research shows that people with firm boundaries have lower daily cortisol levels and higher life satisfaction. It is about learning to say no to the things that drain you so you can say yes to your health.

When to see a professional about stress

If you have reached a point where lifestyle changes alone are not moving the needle, it might be time to talk to a professional. In New Zealand, many people are now exploring doctor-guided support for stress-related issues like insomnia, chronic tension, and anxiety.

At Cannabis Clinic, we take a patient-first approach to these challenges. Our doctors can discuss whether plant-based treatments, like medicinal cannabis, might be appropriate for helping your system find its balance again.

If you are unsure where to start, you can book a free nurse call to discuss your eligibility. We also recommend requesting a health summary from your GP to help us get a full picture of your history. Managing stress is not a luxury; it is a fundamental part of staying healthy for the long haul.

Reference list

1. Sapolsky, R. M. (2004). Why zebras don’t get ulcers: The Acclaimed Guide to Stress, Stress-Related Diseases, and Coping – Now Revised and Updated. Holt Paperbacks.
2. McEwen, B. S. (1998). Protective and damaging effects of stress mediators. New England Journal of Medicine, 338(3), 171–179. https://doi.org/10.1056/nejm199801153380307
3. Steptoe, A., & Kivimäki, M. (2012). Stress and cardiovascular disease. Nature Reviews Cardiology, 9(6), 360–370. https://doi.org/10.1038/nrcardio.2012.45
4. Kivimäki, M., Nyberg, S. T., Batty, G. D., Fransson, E. I., Heikkilä, K., Alfredsson, L., Bjorner, J. B., Borritz, M., Burr, H., Casini, A., Clays, E., De Bacquer, D., Dragano, N., Ferrie, J. E., Geuskens, G. A., Goldberg, M., Hamer, M., Hooftman, W. E., Houtman, I. L., . . . Theorell, T. (2012). Job strain as a risk factor for coronary heart disease: a collaborative meta-analysis of individual participant data. The Lancet, 380(9852), 1491–1497. https://doi.org/10.1016/s0140-6736(12)60994-5
5. Kiecolt-Glaser, J., Marucha, P., Mercado, A., Malarkey, W., & Glaser, R. (1995). Slowing of wound healing by psychological stress. The Lancet, 346(8984), 1194–1196. https://doi.org/10.1016/s0140-6736(95)92899-5
6. McEwen, B. S., & Gianaros, P. J. (2010). Stress- and Allostasis-Induced brain plasticity. Annual Review of Medicine, 62(1), 431–445. https://doi.org/10.1146/annurev-med-052209-100430
7. Noetel, M., Sanders, T., Gallardo-Gómez, D., Taylor, P., Del Pozo Cruz, B., Van Den Hoek, D., Smith, J. J., Mahoney, J., Spathis, J., Moresi, M., Pagano, R., Pagano, L., Vasconcellos, R., Arnott, H., Varley, B., Parker, P., Biddle, S., & Lonsdale, C. (2024). Effect of exercise for depression: systematic review and network meta-analysis of randomised controlled trials. BMJ, 384, e075847. https://doi.org/10.1136/bmj-2023-075847
8. Cohen, S. (2004). Social relationships and health. American Psychologist, 59(8), 676–684. https://doi.org/10.1037/0003-066x.59.8.676