What is the stress response? Your brain and body explained

If your heart has ever thumped before a difficult conversation, or your mind has kept racing at 2am after a hard week, you have felt your stress response at work. So, what is the stress response? Put simply, it is your body's built-in way of gearing up to meet a challenge. Healthdirect describes stress as a common, normal physical reaction to new or demanding situations, and notes that it is also called the fight-or-flight response.

This reaction can help you rise to a deadline or act quickly when something goes wrong. It becomes a problem when it leaves you feeling overwhelmed, or when it keeps firing long after the pressure has passed.

In this article I'll explain what happens in your brain and body when stress hits, why the response can get stuck 'on', and a few simple steps health bodies recommend.

What is the stress response, and why do you have it?

The stress response is a survival system. Harvard Health explains that it evolved to help us survive danger, by giving the body a burst of energy to either fight or get away.

When you are under pressure, your body releases hormones such as adrenaline. According to healthdirect, these hormones create physical changes that help you deal with the situation in front of you. In small doses, that can be useful. It is part of what helps you focus, get moving and follow through.

Here is the part many people find surprising: the trigger does not have to be a physical threat. Cleveland Clinic points out that the response can be set off by psychological pressures such as an important work meeting or a social event. So if your body reacts strongly to an email from your manager, that does not mean something is wrong with you. Your system is simply doing what it was built to do, in a setting it was not originally designed for.

What happens in your brain and body

A lot happens in a very short time when stress hits. Understanding the steps can make the experience feel a little less mysterious.

In your brain

Harvard Health describes how the amygdala, an area of the brain involved in processing emotion, sends a signal to the hypothalamus. The hypothalamus works like a command centre, using the nervous system to prepare your body for action.

In your nervous system

Your autonomic nervous system runs things you don't consciously control, like your heartbeat. The American Psychological Association explains that it has two branches: the sympathetic branch, which revs you up for fight or flight, and the parasympathetic branch, which helps you relax and recover.

Through your hormones

Adrenaline, noradrenaline and cortisol act as chemical messengers. The APA notes that your heart beats faster and more forcefully, blood is sent to your large muscles and heart, and blood pressure rises.

At the same time, some systems are put on hold. Mayo Clinic explains that cortisol slows functions that aren't essential in an emergency, changing immune responses and interfering with digestion, reproduction and growth. Cleveland Clinic adds tissue repair to that list.

The main hormonal pathway is called the HPA axis, which links the hypothalamus, the pituitary gland and the adrenal glands. A 2019 review describes how it keeps the stress response in step with your body's daily rhythms.

What you might notice

Cleveland Clinic lists changes such as:

• faster breathing
• pale or flushed skin
• cold or clammy hands
• goosebumps
• wider pupils
• feeling less pain in the moment

Cleveland Clinic also describes four common patterns: fight, flight, freeze and fawn. You might recognise yourself in one more than the others, such as going quiet and still, or trying hard to keep everyone else happy.

When the stress response stays switched on

The stress response is designed to rise and then settle. Trouble tends to start when it doesn't get the chance. Mayo Clinic explains that when stressors are always present, the fight-or-flight reaction stays turned on.

Research suggests short-term and long-term stress work through somewhat different processes in the body. The 2019 review mentioned above reports that with ongoing stress, cortisol can stay higher, partly because the body clears it more slowly.

Over time, this can take a toll. The US CDC notes that chronic stress may worsen existing health and mental health conditions and lead some people to drink more or use other substances. The NHS describes how long-term or severe stress can lead to physical, mental and emotional exhaustion, often called burnout.

Signs to look out for

Healthdirect lists a range of common signs of stress, including:

• feeling overwhelmed, on edge or unable to stop worrying
• irritability or changes in mood
• trembling, sweating or a racing heart
• changes in sleep or appetite, and exhaustion
• headaches, muscle tension or nausea
• getting sick more often

The NHS also mentions dizziness, stomach problems, trouble concentrating, forgetfulness and avoiding people or places.

A gentle but important note: some of these signs overlap with physical health problems. If you have chest pain, a racing heart that worries you, or any symptom that is new or getting worse, please have it checked by your GP rather than assuming it is stress.

Simple ways to help your body settle

You can't remove every source of pressure from your life, and that isn't the goal. What you can do is give your body more chances to move out of high alert and back into recovery. These steps come from public health guidance rather than any single study, so think of them as starting points.

1. Move your body. NHS inform recommends regular exercise as one way to cope with stress. It doesn't need to be intense. A walk counts.
2. Make room for relaxation. NHS inform also suggests learning ways to relax, and Cleveland Clinic mentions mindful practices such as yoga or meditation.
3. Look at your load. Time management is another NHS inform suggestion. It can help to ask yourself honestly what could be shared, delayed or dropped.
4. Talk to someone you trust. Healthdirect puts talking with someone you trust, alongside relaxation, as a first step before seeking professional help.
5. Notice how you are coping. Healthdirect flags relying on alcohol or other substances, or withdrawing from friends and family, as signs stress may be getting on top of you.

A small reflection to try

The next time you feel stress rising, pause for a moment and simply name what you notice in your body. Perhaps your shoulders have crept up, your jaw is tight or your breathing feels short. You don't have to change anything. Noticing these early signals is often the first step towards responding to yourself with a little more kindness.

When to reach out for support

Healthdirect suggests seeking help if you still feel overwhelmed after trying relaxation and talking to someone, if stress is making everyday life hard, if you are turning to unhealthy ways of coping, if your sleep or appetite has changed, or if you have any thoughts of self-harm or suicide.

It also helps to know that stress itself isn't a diagnosis. Healthdirect describes it as a sign that something else is going on, and notes that chronic stress can sometimes point to depression, anxiety or another mental health condition. GPs and psychologists are trained to recognise when you need extra support.

A good first step is to see your GP or call a mental health telephone service. Your GP can assess how you are going and, if needed, prepare a mental health treatment plan.

You can read more about psychotherapy and hypnotherapy in Newstead and online. If you'd like to talk with me about what is going on for you, you're welcome to book a session in Brisbane or by secure video call, whenever you feel ready.

This article is general information only. It isn't medical or mental health advice and doesn't replace an assessment of your own situation. If you're struggling, please talk to your GP or a qualified mental health professional. If you need support now, call Lifeline on 13 11 14, or 000 in an emergency.