The Ultimate Guide to Stress

What Stress Is (and isn’t).
What Causes Stress
How Stress Works & Why Stress Causes Us So Many Problems

This article is a long study examination of the questions – what is stress and what causes stress.

After reading, you’ll understand why the World Health Organization has labelled stress – The Global Epidemic of the 21st Century”.

You’re going to learn about the physiology and psychology of stress, the stress response and the way our body responds when we are under stress.

This this is NOT meant to be a quick summary of how to avoid stress, because in our 24/7 always-on world, that just isn’t possible.

We’ll cover the recent research, & the discovery that has lead to the development of stress management strategies that are changing the way we live & work in a high-stress environment.

Let’s get started.

(… and for those who are looking for even more detail, the journal references are at the end.)

1. What is Stress?

Stress is a subjective feeling – what I find stressful, may be different to what you find stressful – different people will have different reactions to similar situations.

This feeling of stress is actually a physiological response from our mind and body, to a situation that we find ourselves presented with – it is our body’s way of trying to help us to deal with a particular situation.

Stressful situations (or stressors) are everywhere – we can’t avoid them.

The stressors can be an ongoing situation, such as a difficult work or home environment, or ongoing family, health or financial pressures; or an environmental situation, such as an imminent work deadline.  It could be a psychological stress, such as a persistent worry about losing your job; or it could be an immediate threat, such as a dog chasing you on the street, or the sound of screeching brakes behind you when you are driving!

Our body’s response to these stressors, is what is known as the “stress response” and it triggers a flow of stress hormones within the body that produce significant physiological changes.

Science defines stress as “the functional and structural reactions of the body and mind, when something challenges or threatens our well-being”.

From your own experience, you will be aware that a stressful situation may make your heart beat faster and your breathing become shallower and faster – your muscles may become tense and you may begin to sweat.

2. We’re Under Threat or Pressure – Our Fight or Flight Stress Response

Rather than the question of “what causes stress”, the first step should be understanding our body’s physiological response to stress.

The physiological reactions that are triggered by our bodies when we are faced with a stressful situation, is known as our bodies “stress response”, or also called the “fight or flight response”.

This “fight or flight response” is key to our ability to survive the stress of a significant threatening situation, with our body physiologically, preparing itself to help us “fight the threat” or “flee to safety”.

Based on the research of the American physiologist Walter Bradford Canon, the fight or flight stress response, involves a series of hormones, the brain and part of the nervous system, called the autonomic nervous system, which manages our body’s response to stress, by controlling the involuntary body functions such as blood pressure, breathing and heartbeat.

Importantly, the autonomic nervous system, is divided into two parts, each with opposite effects.

The “sympathetic nervous system”, fires up the body in response to perceived stress and dangers, while its opposite partner, the “parasympathetic nervous system”, calms the body once the danger and stress has passed.

Our body’s response to the threatening situation, begins in the brain, via the sympathetic nervous system.

It works like this …

When Faced With A Stressful Situation …

Our response to stress begins with stimuli from one or more of our five senses – sight, hearing, smell, touch or taste.

Our eyes, ears, nose, for example, take in information about the stress – a screech of tires, a dangerous dog approaching, the smell of smoke at home, the irate phone call from the difficult client – and send this information to the brain’s amygdala to be interpreted.

Our amygdala is responsible for interpreting emotion

Our amygdala is the part of brain responsible for storing, encoding, and interpreting emotion (both happy/good and bad/unpleasant).

The amygdala will then process the sounds and images it receives and if it interprets this information as “danger”, it will then sound the alarm and send a signal of distress to an adjoining part of the brain, called the hypothalamus.

Our hypothalamus is our brain’s emotional command and control center

We can think of our hypothalamus as the stress command and control center – the “seat of our emotions”, with the emotional processing role, that is responsible for balancing our body and maintaining our system’s status quo, through the production of many of the body’s essential hormones.

Our hypothalamus then links through our autonomic nervous system to our endocrine system (metabolism and growth/development), and plays an important role in many essential functions of the body such as, body temperature, thirst, appetite, weight control & digestion, emotions, sleep cycles, sex drive, blood pressure and heart rate, and body fluid balance.

Our autonomic nervous system controls the involuntary bodily functions

Our autonomic nervous system is the part of the nervous system that unconsciously controls and regulates the internal organs, including heart rate, blood pressure, digestion, urination, sexual arousal, heartbeat, and the dilation or restriction of certain blood vessels and small airways in the lungs.

Our autonomic nervous system has two branches:

  • sympathetic nervous system (I call it our “Stress Engine”), which triggers the body’s “fight or flight” stress response, which acts like an accelerator and supercharges the body, so it can respond to perceived dangers.
  • parasympathetic nervous system (I call it our “Relaxation Engine”), which triggers the “rest & digest” response, acting like a brake to our stress response, to calm the body once the danger and stress has passed

So …

Our amygdala has interpreted the information as a danger, and sent the distress signal to the hypothalamus.

The hypothalamus has responded, sending signals through the autonomic nerves and activated the sympathetic nervous system – the body’s “fight or flight” Stress Engine.

So the answer to “what is stress”, is that your feeling of stress, is our body undergoing physical changes to prepare itself to fight (or flee) the dangerous or stressful situation.

3. Our Body’s Fight or Flight Stress Response Has Now Been Activated

With our fight or flight stress response now activated

This is where our adrenal glands (responsible for producing large amounts of the catecholamines – epinephrine, norepinephrine and dopamine), come into action.

Our hypothalamus signals our adrenal glands, which then pump the hormone epinephrine into our bloodstream

The release of the stress hormone epinephrine (also known as adrenaline), into our system, causes a whole raft of physiological changes to take place, designed to help us deal with the stressful event:

  • Our heart beats faster, blood is pumped into our muscles, heart & other vital organs & blood pressure & pulse rate increase.
  • We breathe faster & small airways in lungs open wide to maximize oxygen intake. Extra oxygen is sent to the brain, sight, hearing & other senses are sharper.

Next, the stress hormone & neurotransmitter norepinephrine is released from within our brain’s locus ceruleus.

In parallel, to the release of the epinephrine, the release into our system of the stress hormone & neurotransmitter norepinephrine, acts to further supercharge our body by:

  • stimulating the release of glucose (blood sugar) and fats from temporary storage within our body, to provide extra energy to all parts of our body, and also has the effect of;
  • increasing blood flow to skeletal muscle, reduces blood flow to the gastrointestinal system & reduces kidney function, plus
  • increasing arousal & alertness within our brain, promoting vigilance, enhancing memory & focussing attention, while also increasing restlessness and anxiety. It is also likely that this is the cause of the perception, where in the case of an emergency, the world seems to “slow down” – the reason … since the brain “speeds up”, everything around us seems to “slow down”

All of this happens in a split second

This almost superhuman power you are given to deal with the stress – to jump out of the way of an out-of-control speeding car, all happens before you have had a chance to even think about it!

Mental and emotional threats activate our Stress Response, not just physical threats

It’s important to note, that this Stress Engine/stress response, is activated with not just a physical threat, but with mental and emotional threats as well.  Our body has the same stress response whether we are about to give an important presentation to a new client, or about to knock on the door for a first date crowd, or if we hear a burglar trying to break-in through a window while we are at home.

The stress response is equally as intense even if the threat is totally imagined, such as the spooky shadows that we see after watching a horror movie.

The symptoms of anxiety and panic attacks are also our body’s stress response

The fact that mental and emotional threat can trigger our stress response, is important in understanding the causes and treatments for anxiety and panic attacks.

Scientists discovered that panic attacks may not be a reaction to an acute event, but instead the result of gradual and steady accumulation of stress over a period of months or even years.

Researchers now believe that the anxiety that some people feel, and the panic attacks that can result, are our subconscious triggering the body’s physical stress response, in response to a mental and emotional threat that has built up from earlier situations of high stress.

The Stress and the Threat Continues.  What Happens Next?

After the initial surge of the epinephrine and norepinephrine, the brain makes another decision.

If the amygdala interprets that the danger is still present, it again signals the hypothalamus, triggering it to activate the Second Phase of the body’s stress response.

4. The Second Phase of the Stress Response – “Keep the Pedal to the Metal”

This next phase of the stress response, involves the HPA axis

This second phase, centered around the hypothalamic–pituitary–adrenal axis (the HPA axis), is a complex process of  interactions among three endocrine glands – the hypothalamus, pituitary gland & the adrenal glands – with this feedback and interaction process, further controlling our body’s physiological response to ongoing stress.

The role of the HPA axis is to keep the sympathetic nervous system (Stress Engine) firmly in the “on” position, when the brain continues to interpret that danger is still present.

In response to the “yes, there is still danger”, the:

  • hypothalamus releases CRH. a corticotropin-releasing hormone, which moves down to the,
  • pituitary gland, which responds to this stimulation by in turn triggering the release of ACTH, (adrenocorticotropic hormone). The ACTH then travels to the;
  • adrenal cortex (part of the adrenal glands), triggering it, to then flood the body with the glucocorticoid (steroid hormone), cortisol.

The adrenal cortex then floods the body with Cortisol, which regulates our metabolism and immune response as part of the stress response

Glucocorticoids, specifically cortisol, affect a number of different functions within the body depending on which cell it is acting upon.

Cortisol which is released for several hours following the initial stressor, is critical in the regulation of glucose metabolism, as well as being part of the immune system’s feedback mechanism, acting to reduce certain aspects of immune function, such as reducing inflammation.

In addition, acting on the brain, cortisol also has a significant influence on vigilance and memory formation, as well as impacting salt and water balance & blood pressure.

Cortisol’s primary role though, as part of the body’s stress response, is to replenish the body’s energy stores, so that we can continue to “fight the danger” for as long as we need.

It does this in a number of ways.

Cortisol accelerates the breakdown of proteins into amino acids, which in turn move out of the tissues into the blood and to liver cells, where there are converted into glucose.   This glucose, then becomes the energy source for the central nervous system (the brain) & skeletal muscles during our physical “fight”.

In addition, cortisol

  • stimulates our appetite, especially for high-density calories (sugar, carbs and fat);
  • mobilizes triglycerides from storage and relocates them to visceral fat cells;
  • reduces our cells sensitivity to a hormone called leptin, so we don’t know when to stop eating, as the role of leptin is to communicate with our cells how much fat we need, when to start, and when to stop eating.

So Our Body is Now Primed for Action!

The full effect of these stress hormones, is that our body is now fully prepared to fight (or quickly flee), the immediate physical danger, with physiological changes where:

  • Glucose and fats have been released into our bloodstream, increasing our blood sugar levels, providing extra fuel for our muscles and for our brain;
  • The bronchioles of our lungs get dilated, our breathing is now quicker, as our lungs take in extra oxygen to also better fuel our muscles –allowing us to run further and hit harder. Our tendency to hold our breath when we are stressed and anxious is our body acting to extract as much oxygen from it as we can.
  • Our sight and hearing are now improved, as we become more alert;
  • Our heart is now beating up to 2-3 times faster than normal and our blood pressure rises;
  • Certain arteries narrow, which helps direct blood away from our skin and other organs (that are deemed less important), to our muscles and brain, which have a higher priority function. Interestingly, in our body’s core, blood flow can increase in our skeletal muscles by as much as 1200%, where the emotion of fear increases blood flows to the legs (to run away), while anger tends to increase blood flow to the arms (to fight!!)
  • Our blood platelets are now stickier, so clots can form more easily to minimize bleeding from potential injuries;
  • Our muscles are more tense and tighter, so we can spring into action.
  • Our ability to digest food is restricted and salivation is reduced, which is why we get a dry mouth when we’re scared or anxious and the reason we get a dry mouth when we’re afraid. In addition, the process within our intestines which moves food along our digestive tract slows, which is why stress leads to constipation.
  • We sometimes feel like vomiting, as our body expels food, so as not to “waste” energy digesting food, rather, conserving energy to fight.
  • We may also have the urge to go to the bathroom, as our body looks to expel waste, allowing us to focus on the imminent physical danger.
  • Our sensitivity increases to related emotions such as fear, disgust and anger, making it easier to identify threatening information – which also has the downside of making us prone to over-estimating threats and distorting perspectives – jumping to distorted conclusions when we are feeling stressed or anxious.
  • Body systems not needed for the immediate fight or flight, are constrained, so energy can go where it’s needed,
  • So stomach and intestines cease operations,
  • Repair and growth of body tissues slows,
  • Sexual arousal lessens (we’ve no interest in sex when we’re being chased by a bear … or we’ve spent all day caring for difficult children!!).

Remember, while this physiological supercharged transformation occurs when we feel physical danger, the exact same physiological, stress chemical fuelled response, also caused by everyday things,  such as…

our important client presentation we’re about to give, the argument we’ve just had with our husband/wife/partner/friend/kids; the appointment we’re running late for; the politics we’re caught up in at work; the bills that are due when the money is tight …

5. The Threat & Stress has Passed – Time for Calm to Return

The danger has passed.  What happens next?

OK, the threat and the stress is over – it’s time (in theory), for calm to return.

Our “stress chemical fueled”, supercharged body has done its job and the threat has now passed – we’ve escaped the wild animal, we’ve jumped out of the way of the speeding car, we’ve delivered that critical client report, made-up with our partner after the argument ….

With the threat and stress now over, our body is designed to return to a state of homeostatic balance.

Our eyes and ears capture the sight and sounds of the escaping wild animal (or the car driving away) and once again, sends this information to our amygdala for processing.

Our brain sends the message that the threat has passed and it’s time to switch-off the Stress Engine and switch-on, the Relaxation Engine

Our amygdala interprets this and in turn, tells our hypothalamus that yes, things are OK and the threat has passed.

Our hypothalamus then tells our autonomic nervous system to “switch on” our calming parasympathetic nervous system (switch-on our Relaxation Engine), and so “switch-off” our sympathetic nervous system/Stress Engine and stop the flow of the dangerous stress chemicals that have been flowing through our body.

The activation of our parasympathetic nervous system, triggering our body’s opposite “rest & digest” response, acts like a brake to the stress response, to calm our body after the danger, and return it to balance.

Our parasympathetic nervous system acts like a brake, stops the flow of stress chemicals and acts to calm our body.

Our parasympathetic nervous system/Relaxation Engine uses the neurotransmitter acetylcholine to communicate with the organs throughout the body, switching-off our Stress Engine, halting the flow of the stress chemicals, with the effect that:

  • Our muscles relax;
  • Our heart rate drops;
  • The bronchial tubes in your lungs constrict, slowing our breathing rate;
  • Our saliva increases, digestive enzymes are released and blood vessels to our GI tract open, helping to assist digestion and absorb nutrients;
  • The pupils in our eyes constrict and return to normal;
  • Our urinary output increases,

And our body returns to a state of homeostatic balance, free of the effects of the stress chemicals.

So, doesn’t a supercharged body sound like a good thing?

But surely, a supercharged body, that is switched on and off – optimized and fueled for almost superhuman performance – must be a good thing??

Well – yes and no –  The positive effects of stress are a balance

Stress is not necessarily a bad thing.

When we have a single high stress, high intensity, task or activity that we need to complete – like escaping a wild animal, or jumping out of the way of an out-of-control car, or standing up in front of an audience and delivering an important presentation or speech, or focusing all our efforts to complete an important client report that has a non-negotiable deadline!

As we’ve shown, our stress response is critical to our ability to escape a dangerous situation, or perform under pressure, to deliver an urgent report, or give a presentation in front of a large group.

There are numerous examples of emergency service workers, soldiers, even ordinary citizens, who have performed seemingly superhuman feats, when confronted with a life threatening situation.

Independent of the health impact of exposure to long term stress, we also need to recognize that our performance under even short term stress is a balance.

As we’ve seen, we need physical and/or psychological stimulus to prepare our body for the highest level of performance – our body experiences physiological changes in response to stressors, our alertness increases and our attention sharpens.

So, as our stress and anxiety levels rise, so does our efficiency and performance – however, only up to a point!

The most famous research in this area, performed by psychologists Robert Yerkes and J. D. Dodson, resulted in the “Yerkes-Dodson Curve” below, which showed that as stress continued to increase, beyond the optimal point, eventually performance and efficiency declined.

So stress can be a good thing, when it allows us to tackle a difficult (or dangerous) task, and once the task has been completed, we are allowed to return to a state of calm.

However … stress can be a very bad thing, when our Stress Engine does not switch-off and our body never returns to calm

6. What if Our Stress Engine Never Switches Off

However, stress can be a very bad thing, when our Stress Engine does not switch-off and our body never returns to calm

So, our supercharged, highly stress hormone fueled body is NOT a good thing, when in our 24/7 “always-on, always connected world”, these stresses just blend into one another, with …

that client deadline, our kids problems at school, that argument with our spouse, the diet that we can’t stick to, the pain in our hip we keep ignoring, the layoffs that they’re talking about at work, our parents health problems, those bills that are due, the renovation that is taking forever, our brother’s recent separation, the three coffees we had today, the block of chocolate I ate in one sitting, the terrible sleep we had last night …

The problem is, that research has shown that because of the constant stress that we face on a daily basis, with work, family and financial pressures, deadlines and the external pressures of our “constantly on” 24/7 lifestyle, our sympathetic nervous system/Stress Engine never switches off!

Our Relaxation Engine never switches on, so our Stress Engine never switches off.

And as a result, the stress chemicals triggered by our stress response – the epinephrine, the norepinephrine and the cortisol – continue to flow through our body for months, years or even longer.

It’s the long term exposure to these dangerous stress chemicals, that cause serious health problems

So, we’re now beginning to understand the problem – the terribly damaging serious damage to our health, which has been caused by the long term exposure to these stress chemicals in our body.

This long term, bad stress is called chronic stress and it is extremely dangerous to our long term health.

Chronic stress is the result of continued and ongoing exposure to stressors

The long term and ongoing chronic stress, results in the body being in an almost permanent state of stress hormone fueled “fight or flight” response.

While acute stress (the short-term, one-off event stresses) can be sometimes “exciting”, chronic stress is the most dangerous and unhealthy form of stress, and can make many destructive physiological changes to your body and mind, can seriously effect your short and long term physical and mental health.

It is brought on by ongoing and highly stressful situations such as an unhappy marriage or relationship, long term financial stress, serious chronic illness, early childhood experiences, difficult workplace environments or serious family problems.

The physiological and psychological damage to our body that results from chronic stress can be life threatening, with serious illnesses such as heart attack, stroke and cancer, as well as serious psychological illnesses including clinical depression and post-traumatic stress disorder, all linked in research studies to exposure to chronic stress.

7. So … What is the Solution to Living and Working Under Stress?

So how then do we grow and succeed, healthy and happy, living and working in a 24/7 always-on stressful environment?

So now that we’ve begun to understand the problem of stress, we can begin to understand what we must have in a stress management solution.

In our 24/7 always-on “real world”, our lives will always be stressful – with work, family, relationship, finance, social, health and other challenges, we can’t simply walk away or escape the situations that cause us stress.

The answer therefore, is stress management solution that allows us, at any time, to control our body’s response to a stressful situation and to the symptoms of stress when we feel them.

A system that allows us to:

  1.  switch-off our “Stress Engine” and stop the effects of the dangerous stress chemicals in our body, and switch-on our body’s “Relaxation Engine” and the flow of the neurotransmitters that encourage the relaxation and healing process.
  2.  relieve the symptoms of stress that we feel, and switch-on calm, when we’re feeling tense and frustrated; switch on energy when we are exhausted; switch on sleep, when our mind is still spinning; and switch-on concentration when our brain feels scrambled.
  3.  repair the damage done to our body by past stress, but more importantly, to defend and protect our body against the effects of future stress.

A stress management solution that will allow us to live, work and love life – healthy and happy – within our 24/7 always-on high stress environment – safe from the damage that stress causes.


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  8. Ethan Moitra, Ingrid Dyck, Courtney Beard, Andri S. Bjornsson, Nicholas J. Sibrava, Risa B. Weisberg, Martin B. Keller,    Impact of stressful life events on the course of panic disorder in adults, Journal of Affective Disorders, Volume 134, Issues 1–3, 2011,

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