What is stress and how can it affect our body?

“I’m feeling stressed out” or “I’m a bit stressed at the moment with …” are phrases we often hear. Though what really is stress and how does it affect us?

It is important to acknowledge that stress is a normal and natural part of living a full and meaningful life. We all encounter some level of stress when doing things that are important to us. It could be going for that job interview, speaking in front of an audience, or having a challenging conversation with a loved one. Usually stress is manageable (or even helpful). However, it is also possible for stress to become an unhelpful barrier keeping us from those things that really matter.

What is Stress?

The term stress, as it is often used in day-to-day conversation, can encompass a broad range of emotions, thoughts, and physiology which makes it a little tricky to pin-down to a single definition. Scientist Dr. Hans Selye is generally considered the first person to use the concept of stress in modern medicine and he defined it as the body’s reaction to demands placed on it. Dr Selye made an important distinction between distress – an unhelpful reaction to stress and eustress – helpful reactions to stress.

How does our Body Responds to Stress?

Our body’s stress response begins in the brain.

The amygdala is a part of the brain which interprets sounds and images. When it perceives a threat, it sends distress signals to another part of the brain called the hypothalamus. The hypothalamus in turn sends a message to the adrenal glands in the kidneys, which then pump epinephrine (also commonly known as adrenaline) throughout the body.

Epinephrine brings on a number of physiological changes in the body, which you are likely to be familiar with.

The heart starts beating faster, pumping more blood through the body’s muscles and vital organs. Breathing also become quicker and little blood vessels in the lungs open up to allow more oxygen to be absorbed with each breath. Some of this extra oxygen is sent to the brain, which increases alertness. Epinephrine also causes sugar and fats to be released from storage and this increases the amount of energy available to the body. These automatic physiological changes happen very quickly are sometimes referred to as the ‘fight or flight’ response. These changes in your body are designed to help you avoid a dangerous situation ( for example – jump out of the way of an oncoming car) or resolve the challenging situation that you find yourself in.

Once the initial epinephrine (or adrenaline) surge subsides, the hypothalamus then activates the second part of our body’s response to stress called the HPA axis (made up of the hypothalamus and pituitary gland in the brain, and adrenal cortex in our kidneys).

If the brain still perceives that there is a threat, then the HPA axis triggers a number of hormonal responses which result in the release of cortisol. Cortisol keeps our body ‘on alert’ and also increases some immune system and memory functions.

Once the threat is resolved and the brain no longer perceives a threat, cortisol and epinephrine levels reduce to baseline levels. Subsequently, heart rate, breathing rate, oxygen, and energy levels also return to normal.

So, What’s the problem with Stress?

Most of the time, stress is no problem at all. In fact, the stress response is our body’s way of giving us the ‘extra boost’ needed to be able to successfully navigate challenging situations and continue to grow and build confidence in our abilities. Remember Dr. Hans Selye’s concept of eustress – or positive reactions to stressful situation.

However, if the brain continues to perceive an ongoing threat, the body can get ‘locked into’ a prolonged stress response. This can be distressing and hold us back from engaging with life in a full and meaningful way. Chronic exposure to higher levels of epinephrine (adrenaline) and cortisol are sometimes associated with poorer mental wellbeing and poorer physical health outcomes.

How to know when to consider professional help managing stress?

It may be useful to consider seeking professional support if you find that stress is adversely impacting your work performance, relationships with family and friends, or your emotional wellbeing.


Australian Government Health Direct Website: https://www.healthdirect.gov.au/stress

Harvard Medical School Health Publications: http://www.health.harvard.edu/staying-healthy/understanding-the-stress-response

The Australian Psychological Society Stress Tip Sheet: https://www.psychology.org.au/Assets/Files/StressTipSheet.pdf

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