Those who know me will most likely know that my PhD research is focussed on studying a factor called stress. Something that we have probably all had a taste of. But when we talk about stress we are often referring to a psychological state and rarely are the physiological aspects of stress considered. Many people have heard of the fight or flight (and more recently considered, fright/freeze) response, and when provided with the classic saber tooth tiger analogy they can somewhat appreciate the possible benefits of stress. In that situation it is quite simply survival. But at what point does stress become too much? At what point does stress go from friend, to foe?
Stress is typically defined as a challenging situation that poses some sort of threat – think threat to survival, identity or resources. In a previous post I explained an appraisal process in coping – this process features here as well. When the challenging situation is perceived to be demanding responses or resources beyond our capability – stress is the result.
Stress typically falls into two categories, acute and chronic. Stressors that are short lived (e.g. minutes, hours, days) are considered to be acute. Whereas those that last longer (e.g. weeks, months, years) are deemed chronic. Herein lies the key as to why stress can be both helpful and a hindrance. This is due to the physiological ‘stress response’ that takes place within the body when faced with a stressor. Sometimes we can feel our bodies responding to stress – shaky hands, sweating, wobbly knees, increased heart rate… But these outcomes are only the tip of the iceberg when it comes to what our bodies do under stress.
In simple terms, when the brain detects a stressor an area of the brain called the hypothalamus releases corticotrophin-releasing hormone (CRH) which activates the pituitary gland causing adrenocorticotropic hormone (ACTH) to be released into the bloodstream. This is turn travels to the adrenal cortex where cortisol is released. The body activates these systems and produces hormones such as cortisol and adrenaline to help us cope with a stressful situation. Most people know that adrenaline is helpful and can aid survival. We’ve all heard the stories of mothers lifting heavy objects off their trapped children.
But cortisol is the lesser known hero of the stress response. In acutely stressful situations cortisol is our friend as it plays a large role in preserving our resources. This happens as cortisol shuts down unnecessary functions like reproduction and digestion to ensure that all energy is directed towards dealing with the stressor being faced. Research has also found that this hormone can enhance immunity, depending on the conditions in which stress is experienced. Again, from an evolutionary perspective this is particularly helpful, the body is preparing for damage or injury, and thus increasing its resources to fight infection (as a result of a swipe from that saber tooth tiger perhaps?).
So in these instances it is easy to see how stress is our friend. But like all things, moderation is key. When we look at the body under chronic stress it is a very different story. The stress response is primarily an adaptive coping mechanism, however when over activated by repeated stressful encounters it can become damaging. This is where a factor called Allostasis comes in.
Allostasis is the body’s ability to remain stable through change, that is, for the body to respond to stress effectively and then regain balance once the threat has passed, in a similar way to homeostasis. When repeated exposure to stress causes repeated activation of the body’s stress system, this can result in ‘allostatic load’ which in turn can lead to cumulative damage and general ‘wear and tear’ on the body.
Coming back to cortisol, when the body is under allostatic load and thus the stress response is firing frequently, the levels of this hormone circulating in the system can become elevated. Whilst cortisol in the first instance can have an enhancing effect on the immune system, over time raised cortisol levels have the opposite effect and lead to immune dysregulation which contributes to that wear and tear of the body and can lead to a number of negative health outcomes. Cohen and Herbert (1996) found that chronic stress was associated with increased susceptibility to cold, flu, herpes virus and chickenpox, and Stokanovich et al (2008) have linked psychological stress to the development of autoimmune disease.
Therefore, acute stress can enhance our bodies and minds, creating the awareness and physical energy required to manage our situation. Chronic stress on the other hand, can lead to more detrimental effects and put our health at risk.
So, like many things in life that can impact your health, the difference between stress being ‘good’ or ‘bad’ for you all depends on the intensity and duration of the stressors that you are experiencing. Given the evidence for the health impact of stress it makes sense that so many resources are being given to initiatives and programs that aim to prevent, reduce and alleviate stress.
I think this research is fascinating, and it is important to remember that every single body is unique. Stress will affect us all in different ways, and our antidotes to stress will be different too. Providing we can begin to manage our stress levels and be observant of our internal and external environments, we have a good chance of reducing the health impact of our stressful modern lives. Knowledge is power friends!
Til next time 🙂