'Stress Response Series' Part 1: How do we respond to stress?

12 Apr 2023

'Stress' has become a ubiquitous concept and term, bandied about with (ironically) careless abandon: 'I'm so stressed'; 'He really stressed me out'; 'I've got to stop being so stressed'. We talk about stress all the time, but what exactly is stress? What are the differences between acute stress and chronic stress? And why does it matter?

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Imagine standing inside a lighthouse, looking out to the ocean.

The sea is rough but well below the pier: you are in no danger.

You close your eyes, taking in the sounds of the ocean, when you become aware of a rumbling, with what was a faint roar becoming louder and ever more rageful.

The wind whips up, forcing the waves into frightening shapes.

You look out to see a monster of a wave approaching: an unimaginable wall of water hurling its terrifying attack towards you.

This is not a time for thinking things through.

Without thinking, you find yourself in a state of either running away, bracing yourself for the onslaught, or collapsing.

All three of these strategies operate purely to protect you and ensure your survival.

Our bodies are amazing, but what are the processes involved here?

Let's take a look.

1. Running away / bracing:

  • Your heart beat and heart rate increase to pump blood faster.
  • The blood is taken away from the organs and sent to the limbs and brain so you can think, run, jump and hold on for dear life.
  • There is an increase in blood sugar to accelerate thinking and drive sugar into the muscles so you can act quickly.
  • Your airways dilate to increase oxygen and the delivery of nutrients.
  • Meanwhile, your body make its own glucose to provide your organs and cells necessary energy to meet the stress.
  • Your pupils dilate so you can see clearly.
  • Your digestion is inhibited (saliva glands, stomach acid and digestive activity stops).

This is sympathetic nervous system activation.

2. Collapse:

  • Pupils contract, resulting in blurred vision and a narrowing of your visual field - you can only see what is directly in front of you.
  • Saliva is stimulated so you can quickly digest food which can result in nausea, vomiting and loss of bladder or bowel control.
  • Airways constrict, your heartrate goes down and your blood is moving much more slowly.
  • The blood is moved away from the the limbs and and sent to the organs. This both conserves these critical areas, and minimises blood loss if you are injured. Your skin is likely to be pale and clammy.
  • Your heart rate and blood pressure drop, resulting in reduced blood flow to your brain. This can result in lightheadedness or losing consciousness altogether.

This is parasympathetic nervous system activation.

Both sympathetic and parasympathetic nervous system responses are designed to protect us and ensure our survival in the face of stress.

These systems do a great job of supporting us to respond to acute stressors. However, when stress is ongoing, these systems become dysregulated, leading to significant impacts on our overall health.

I stress about stress before there is any stress to stress about.


'Stress' has become a ubiquitous concept and term, bandied about with (ironically) careless abandon:

  • I'm so stressed.
  • He really stressed me out.
  • I've got to stop being so stressed.

We talk about stress all the time, but what exactly is stress?

What is stress?

Stress is a threat, real or perceived, to our physiological or psychological wellbeing.

In their 2022 report, the Australian Institute of Health and Welfare, describe stress as:

  • "a common and normal physical response to challenging or new situations​
  • (that) has both mental and physical aspects and can be triggered by different life experiences". ​

These physiological responses are broadly orchestrated by the polyvagal system and the hypothalamus, pituitary and adrenal systems (otherwise known as the HPA axis).

They are a brilliant solution when we are in danger; in a state of acute stress.

Acute vs chronic stress

In an episode of acute stress, such as the incident with the wave described above, the immediate short-term response involved a cascade of neurobiological events in order to ensure protection and survival.

This facilitates a protective response: running away, bracing yourself for the onslaught, or collapsing.

This stress response is designed to protect you from immediate danger: things like, running away from a lion, or jumping out from under a falling tree.

However, when we are exposed to prolonged periods of stress, chronic stress, the activation of these mechanisms can cause serious harm to our physiology and mental health, resulting in:

  • inflammation
  • heart disease​
  • mental health conditions
  • digestive, hormonal and immune system issues.

Continuous stress without relief can result in a condition called distress – a negative stress reaction that can lead to physical symptoms such as headaches, loss of appetite, increased blood pressure, chest pain, sexual dysfunction, and problems sleeping.

Sitting in this chemical stew of chronic stress is clearly harmful.

What can we do about it?!

Check out this blog to find out about the stress response cycle and how it can help you to prevent states of chronic stress.

Related Resources

Header image: Marcus Woodbridge