Stress is a part of our daily human experience and is associated with a range of emotional, mental and physical demands. It is the non-specific response of the body to any demand and whilst stress is commonly associated with an emotional or mental state, stress impacts our minds and bodies in a myriad of ways, from the cellular level to our highest cognitive functions. In fact, the human body processes stress in an identical manner, regardless of what the actual stressor may be! Therefore, pressures placed on the body by exercise, financial matters, emotional situations, poor nutrition and inadequate sleep all are processed as stress in your body. That is, our body processes are identical despite the great variability in our experience.
So what actually happens to the body when it undergoes stress?
From a purely biological perspective, stress refers to the adaptation of an organism to changes in the environment. This process occurs in a complex manner at the most basic cellular level. In terms of our central nervous system (CNS), stress activates our sympathetic nervous system also known as our ‘fight or flight’ response. The CNS instantly tells the rest of your body what to do, marshalling all resources to the cause. In the brain, the hypothalamus gets the ball rolling, telling your adrenal glands to release adrenaline and cortisol.
Adrenaline has a fast-acting effect on the nervous system and is often involved in an immediate stress response and should last no longer than a few minutes. Cortisol is more potent and longer lasting chemical. It has similar effects to adrenaline but is used to deal with longer lasting threats, thus it has a greater potential for effect.
The effect of stress on pain perception
The hormones released in the stress response have a profound effect on the nervous system. The exact mechanism of how stress affects pain is unclear, however research has shown that stress, particularly when coupled with anxiety, is associated with reduced pain threshold.This means that less stimulus can elicit a pain response. For example, if you usually feel some neck or back pain after sitting at your desk for one hour, it may come on after only 30 minutes if you are chronically stressed. Similarly, high stress levels can cause a greater pain response even if the stimulus is the same. This means that if bending forward usually gives you a pain you would rate as 3/10, it is possible that, when in a stressed state, the same action will cause a 4+/10 pain rating. It is even possible that a stimulus usually perceived as painless, a light touch for example, may be perceived as painful in a stressful condition.
Acute stress and the body’s response to it is a completely normal process; it is required to manage through times of need. A problem arises when stress changes from acute to chronic. Chronic stress is when a stressor is constantly present and you are unable to proceed with the relaxation response that follows acute stress. This means that your stress hormones are continually elevated and your sympathetic nervous system is continually firing, which can lead to several health complications.
Chronic stress has been associated with increased risk of:
- Fatigue & Tiredness
- Anxiety & Depression
- Digestive problems
- Heart disease
- Sleep issues
- Weight gain by decreased metabolism
- Memory & Concentration impairment
- Adrenal Fatigue
- Muscular aches and pains
Inflammation is a natural process that helps to support healing and restoration of health. It is a defence mechanism or response by the body in particular the immune system to a harmful stimuli or perceived threat. Acute inflammation is healthy natural process; think of when you have an ankle sprain and it swells up, over a period of time that swelling will decrease and it actually initiates the healing of the damaged tissue. Chronic/systemic inflammation is a problem as it leads to a whole host of problems such as increased risk of cardiovascular disease, auto immune disease such as rheumatoid arthritis, diabetes and cancers just to name a few.
Cortisol suppresses inflammation during a stress response. If it is present in the blood for long periods, the body develops a resistance to cortisol and does not respond to it properly. Instead, it ramps up production of substances that actually promote inflammation, leading to a state of chronic inflammation. At a physiological level when someone is stressed and resistant to cortisol, specific enzymes are released, which lead to a cascade of processes that allows for secretion of inflammatory products into the bloodstream. These inflammatory markers are spread across the body and will settle in different places.
As part of the fight or flight response, when the sympathetic nervous system is in action, a number of physiological processes that are not considered vital for survival slow down temporarily. These non-vital systems include the digestive system, which is often slowed or even placed on hold to allow for the energy and blood flow this process would usually require to be redirected to more vital areas. This is part of the reason that people will report gastrointestinal distress such as nausea or diarrhoea following exposure to an acute stressor. Chronically elevated levels of stress therefore appear to be related to many chronic gastrointestinal issues.
Reduces cognitive ability:
Studies have shown that an increase in the stress hormones has a direct correlation with the memory impairment plus other cognitive functions. One of the theories behind why this might be the case is related to the glymphatic system, a system which has only been identified by researchers in recent years. The role of this system is to remove waste and toxins that build up around the brain throughout the day, with one example of these products being unnecessary inflammation. This system can only work when you are asleep as the flow of cerebrospinal fluid is greatly increased and the interstitial space changes from 20% of the brain volume to 60% in volume. Therefore, stress which impacts on an individual’s sleep, is likely to result in memory impairment.
Decreases immune function:
The immune system is the body’s form of defence. It is comprised of organs, tissues, cells and cell products that all work together to fight harmful substances like the pathogens that cause infection and disease. Current evidence indicates that there are two main pathways in which stress effects our immune systems. These complex systems include many contributing factors that future research will hopefully identify. One known mechanism in which the immune system is impaired is via the increased production of inflammation – as discussed above.
When the fight or flight nervous system is under action, energy and blood flow is sent to other process or body parts that are seen to be more important at that time. The hormone cortisol actually inhibits immune cell signalling which is the way in which the immune system talks to itself, therefore effecting its ability to fight off antigens, making people more susceptible to illness. One study has shown that those who suffer from chronic stress are twice as likely to get the common cold or flu. Another study has shown that wound healing rates decrease by as much as 40% when one is stressed.
Come in and see our Osteopaths at Absolute Health & Performance in the heart of the Melbourne CBD to help understand how stress can be contributing to your health and learn some ways in which stress can be managed appropriately.
Written by Absolute’s Osteopath Ashley Gudgeon