Stress is a threat, real or perceived, to homeostasis – the body’s normal functional equilibrium. This pervasive phenomenon elicits a physiological response, which, if disproportionate, either in magnitude or duration sustained, can be detrimental to the body. The body has mechanisms in place to repair the resulting damage once the stressor has passed, but chronic stress disrupts these mechanisms. As we age, the delicate balance between damage and restoration progressively tips, and impairments accumulate. Prolonged stress can affect how quickly we age and when we begin to show signs of pathology. Nearly two thirds of diseases are thought to be triggered by stress, and daily stress can increase an individual’s risk for developing non-communicable diseases, or NCDs. An NCD is a disease that is not infectious and not communicable, as it is not caused by an infectious agent. Examples of such diseases include heart disease, obesity, and osteoporosis.
The stress response evolved to act in short spurts to increase an individual’s odds of survival in the face of immediate danger. It works by temporarily optimizing the body’s performance through the neglect of digestion, growth, reproduction, and immune functions. When this system is abused through the presence of chronic stress, and high levels of glucocorticoids are maintained for long periods, this neglect of important body maintenance functions can lead to various disorders, including high blood pressure, diabetes, and hyperthyroidism.
One mechanism by which stress can lead to certain NCDs is by raising the appeal of an unhealthy lifestyle. Individuals employ coping methods to alleviate stress in the moment, and eventually pay the price for the cumulative impacts. One study found that financial stress over a prolonged period increased an individual’s risk of becoming obese by 20%. Another found that nurses with work schedules at unfavourable hours were more likely to practice unhealthy behaviours, including alcohol consumption and smoking. These nurses, especially those that were female, were also more likely to eat due to stress, and these meals were less likely be nutritious. Unsurprisingly, the authors’ major finding was that nurses with unfavourable schedules were more prone to obesity.
Persons experiencing chronic stress are also more likely to take up smoking and ingest more alcohol. However, research suggests that these lifestyle aspects, while detrimental to health, are not the primary cause of an increased risk of stroke and transient ischemic attack. Stress is that primary cause.
There has been little evolution in the body’s stress-coping mechanisms over the past several thousand years, despite changes to society and demands from individuals. As a result, a person’s physiological response to the stress of being late for an appointment, worrying about their mark for a test, or losing their job resembles that which occurred in a time when stress was acute and very extreme – potentially involving risk of death from a predator or from starvation.
In developed countries such as the USA and Canada, NCDs are the most common cause of death, and countries around the world that are shifting from agrarian to post-industrial societies are witnessing increasing prevalence of these disorders. Curiously, almost 80% of deaths due to NCDs occur in countries of low to mid-level incomes. Perhaps this is a result of increasingly sedentary lifestyles and rapid urbanization.
More than half of the world’s population lives in cities and this number is increasing. Studies demonstrate that individuals brought up in cities have a different response to stress compared to those brought up in a rural environment, even if these people moved to cities as adults. City-dwellers have a relatively large amount of firing in the amygdala and cingulate cortex when presented with a social stressor, indicating a stronger emotional response. Possibly this difference could mean that individuals who grew up in cities are more prone to mental disorders.
Given the lag in the evolution of the stress response, it cannot be expected that individuals will experience less activation of the stress response systems in the face of adversity. This fact highlights the importance of work-life balance and taking care of one’s mental health.

Body Systems vectors from Adobe Stock and many of the other images are from Pixabay and FootageCrate