Overview of stress
Introduction to the “stress systems”
Our physiological functioning, including stress / activation and relaxation / recovery, is regulated through a complex interplay between our brain and two physiological pathways.
The first pathway is the autonomic nervous system (ANS) which is involved in regulating most of our automatic processes (e.g. heart rate, blood pressure control, digestion, pupil dilation and so on). The ANS is divided into two branches; the sympathetic (SNS) – quick response mobilising system, also known as the fight & flight response – and the parasympathetic (PNS) – more slowly activated dampening system, also known as the rest and digest and calm & connect – branch (see the autonomic nervous system article for more info).
The second pathway is the hypothalamic-pituitary-adrenocortical system (HPA-axis) which regulates a slower but longer lasting stress response (including the release of cortisol) and also regulates a range of hormones as part of a normal 24-hour wake-sleep cycle (see the HPA-Axis article for more info).
When we are presented with a stressor, challenge or threat our ANS responds first and fast. The SNS kicks into gear and messages the adrenal gland to release adrenaline and noradrenaline. Adrenaline decreases fast (less than 10 minutes) so if we need to sustain an increased level of activation (the stressor, challenge or threat hangs around), the HPA-axis takes over and triggers the adrenal gland to release cortisol.
An often overlooked component of an effective and healthy stress response is post-stress recovery. The SNS was only ever designed as an acute / emergency response with fast but temporary activation and even the longer stress response mechanisms of the HPA-axis were not designed to remain activated indefinitely. This post-stress recovery is not just important to allow our body to heal, rebuild and recharge but also for the stress hormones to be able to come down to normal levels.
A normal stress response is characterised by a wave form - each time allowing our system to downregulate
When these systems function optimally
These “stress” systems were originally "designed" as automatic systems to keep us alive and support a way of living that is juxtaposed to modern living. Our ancestors’ way of living followed the wave-pattern associated with an effective and healthy stress response (refer above illustration) which enabled the systems to function optimally. This optimal functioning involves two dynamics:
Balance between the sympathetic and parasympathetic branch of the nervous system.
When the sympathetic branch is dominant we move into what we call a catabolic state - the breakdown of molecules into smaller components which releases energy but also breaks down our cells. Parasympathetic dominance shifts us into an, opposite, anabolic state - the rebuilding of cells, recovery of energy and healing of our body. A good analogy, which is reflected in the body resources chart in your Firstbeat Lifestyle Assessment, is that of a battery. The SNS uses up and depletes battery power, whereas the PNS recharges the battery. The normal stress response wave pattern allows time for both branches to be sufficiently active, keeping our battery nicely charged and our body in a good state of repair.
a healthy and balanced lifestyle enabling our battery to stay nicely charged and enabling our body to stay in a good state of repair
Keep hormone levels nicely fine-tuned to support our wake-sleep cycle and healthy functioning
The various hormones in our body are engaged in a fine-tuned interplay that directs our wake-sleep cycle and the operation of our organ systems, including our immune and inflammatory systems.
Increased cortisol levels during a sustained stress response increases our ability to respond to the challenge (refer illustration) but it also suppresses the immune system and serotonin (our good mood neurotransmitter).
Highly functional of course and when we allow post-stress recovery after each challenge cortisol levels can return to normal. Blood sugar and blood pressure levels stabilise and the immune and “good mood” systems fire up again.
Modern-living and the stress systems
Stress in itself is of course normal and functional - without a certain amount of activation we are unable to perform and live life to the fullest. Labeling stress as "bad" and something that should be avoided is a gross oversimplification and not the answer.
However, our fast-paced always-on lifestyles have created a way of living that is associated with the prolonged stress response pattern (refer illustration at the top of this article). As the stress systems have seen very little evolutionary change this upsets the good functioning, balance and resilience of these systems which "automatically" lead us to poor health, impaired mental well-being and compromised performance.
Insight: Our human nervous systems function on "default-wiring" that is designed to keep us alive, not to make sure we thrive.
The nervous system is sophisticated in its operation but doesn’t distinguish that well between a physical stressor (e.g. exercise) and other sources of stress (e.g. a stressful meeting at work). The sources of non-physical stressors are widespread and include social, relational, environment, emotional, mental, nutritional, social media / information, financial, work / study and performance stresses.
A such there is a constant demand on our stress system often combined with a habit of not taking regular breaks. The recovery part of the stress response doesn’t occur at all or is interrupted by yet another stressor which leads to two big problems.
Firstly our sympathetic nervous system becomes dominant and the parasympathetic nervous system disappears into the background. Our nervous system becomes imbalanced and dysregulated and stops functioning properly. Our ever so important “brake” withdraws and there is insufficient rebuilding of cells, recovery of energy and healing of our body.
A lifestyle characterised by prolonged stress responses leading to depletion of body resources and lack of body repair
This becomes a downward spiral as a dysregulated nervous system also makes it less effective in responding to stress and reduces its ability to put the brake on.
An important side note also on the two forms of stress; positive stress (eustress) and negative stress (distress). When we experience negative stress we feel tension, which makes us feel unsure, out of control or under pressure. Whereas when we experience positive stress we feel challenged in a positive way, it motivates us to meet the challenge and we are self-assured and feel capable. Positive stress can give us various benefits including for example increased self-confidence, new capabilities that set us up for better living standards, enhanced mood etc.
At a physiological level, there is however not much of a difference between these two forms of stress. As such, good recovery is needed to balance both eustress and distress.
Secondly, we run the risk of cortisol levels becoming chronically elevated. Cortisol levels will decrease only if adrenaline comes down (no new challenges) and stays low long enough (good recovery after stress).
Constant stressors and lack of good recovery in between keeps cortisol levels chronically high. This has a very harmful flow on effect as it can impair our sleep (early awakenings) and changes in insulin sensitivity (diabetes type 2), weight gain as well as cardiovascular, immune system and digestive problems.
In relation to sleep, elevated cortisol levels can upset the natural interplay between melatonin and cortisol. Melatonin naturally declines and cortisol naturally increases early in the morning as part of our sleep-wake cycle. When cortisol levels are too high, the cross-over between the two occurs too early and we find ourselves wide awake and ready to start the day at around 4am - losing a few important hours of sleep in the process.
Adopting a healthy lifestyle therefore is all about helping these ancient systems to operate well also in our modern world and learning how to consciously influence these process in positive ways to compensate for the reality that they were never designed (or evolved well enough) to enable us to thrive.
Summary of the impact of chronic stress
Excessive and prolonged stress, without the appropriate amount and frequency of recovery, is detrimental to our health, longevity and performance.
According to a 2016 World Health Organisation study and other research, most of the top 10 causes of death are directly linked to chronic stress. The exact mechanisms for this are complex and not fully understood but chronically elevated cortisol levels undoubtedly play a key role. As mentioned, it suppresses the immune system, raises blood sugar level, impacts mood and can interfere with sleep and therefore inhibit sufficient and good quality recovery. This chronic cortisol elevation, at least in part, explains the relationship between chronic stress and digestive problems, cardiovascular health and a wide range of other illnesses.
The other key factor at play involves the vagus nerve. This important nerve is further explored in the The power of the Vagus Nerve (deep dive) article. In a nutshell the vagus nerve is our largest nerve that wanders (vagus is latin for wandering or straying) through the entire body and connects our brain and all our primary organs. The parasympathetic nervous system exerts its control through the vagus nerve and this nerve is directly connected into the immune and inflammatory system.
With prolonged exposure to stress without sufficient recovery the sympathetic branch of the nervous system becomes more and more dominant and the parasympathetic brake withdraws and the vagus nerve becomes less and less active. As a result the vagus nerve becomes less effective in keeping our inflammatory response under control. Our inflammatory response goes into overdrive and causes chronic inflammation and / or inflammation flare-ups (e.g. hives).
Also, Elizabeth Blackburn and Elissa Epel have extensively researched telomeres, the protective end regions of every chromosome (the part of your cells that hold your genetic code). Telemores, which shorten with each cell division, help determine how fast your cells age and when they die, depending on how quickly they wear down.
They established that chronic stress shortens your telemores and does so faster.
This effect is the same whether you actually experience the stress or whether you are feeling threatened by it, even if the stressful event hasn't happened yet! They also found that shorter telomores are associated with a weaker immune system and more inflammation!
Exposure to chronic stress also increases the risk of burnout. Burnout is a syndrome characterized by exhaustion, cynicism, and reduced effectiveness caused primarily by excessive and prolonged stress (of any kind, not necessarily limited to job related stress).
It is not just our health that is adversely impacted by chronic stress. Our performance and productivity is also significantly affected and this is best explained through the Yerkes–Dodson law.
This “law” shows the empirical relationship between arousal and performance, originally developed by psychologists Robert M. Yerkes and John Dillingham Dodson in 1908.
The law dictates that performance increases with physiological or mental arousal, but only up to a point. Strong and in particular sustained (chronic) stress erodes performance.
It is again the vagus nerve that plays a vital role in this performance dynamic. Those of use with a good "vagus profile" perform better psychologically (mood), cognitively (memory, speed etc), socially and relationally as well emotionally (regulation).
Stress management is an oxymoron
Maintaining good functioning, balance and resilience in the various systems involved in the regulation of our stress response is key to our health, well-being and performance.
A logical conclusion to draw is that we must focus therefore on "managing our stress" which has become a popular topic (a Google search for stress management return over a billion results!). However stress and management is an oxymoron. The minute we manage, try to get rid of stress, force ourselves to avoid it or even want to control it or fight against it, apply a lot of effort to reduce it etc, we ironically activate our sympathetic nervous system and make things worse.
An alternative mindset and language involves allowing ourselves the space and time for our physiology to naturally downregulate, to permit ourselves to have enough sleep and regular breaks, to guide a healthy physiological response to a challenge etc. This approach quite naturally allows the parasympathetic nervous system to come online, take over and downregulate us.
This doesn’t mean of course that examining the sources of the stresses in our life is not a good strategy. Quite the opposite, it can be a very useful exercise to do an inventory of the sources of stress in our life and taking steps (where possible) to eliminate, reduce or mitigate. At a minimum understanding the stresses in our life can help to create extra motivation to prioritise good self-care and recovery. The Holmes-Rahe Stress Inventory survey or the My Positive Health wheel are some tools to take stock of your sources of stress.
Key to an effective relationship with stress also involves adopting sustained healthy lifestyle habits that support good systemic functioning. This is where physical activity / exercising right, enhancing recovery, good sleep and eating well becomes the center of our attention.
