Summary: there are three main types of stress. Also, the brain triggers the release of stress hormones, such as cortisol, and reallocates energy to ensure survival. However, psychological stress can have a long-term devastating effect on the body and the mind.
There is more than one type of stress and each one affects you in different ways. For a general definition of stress I encourage you to read my previous post: what is stress?.
Let’s go straight to the point. There are three types of stress:
1) Acute stress – an extremely stressful event that demands an immediate physiological adaptation to ensure survival (e.g. a person jumping to avoid getting hit by a car when crossing a street or an antelope sprinting from a hungry lion in a savanna).
2) Chronic stress – a prolonged period of pressure in which an individual has no control over the situation (e.g. a farmer with less food caused by a drought that devastated his crops).
3) Psychological stress – a sustained emotional perception that generates a feeling of anxiety or discomfort towards life events (e.g. parents divorce, death in the family, made redundant at work) or social disruptions (e.g. long and busy commutes, poor working conditions, beginning or end of relationships).
The good news is that the body can reasonably withstand adaptation for short-term emergencies, i.e. acute and chronic stress. The bad news, though, is that psychological stress creates detrimental effects on your body and mental health; it might start as flu or a bit of anxiety and depression symptoms. Ultimately, psychological stress could lead to ulcers and even cancer .
What happens in the body during a stress-response?
Both dwelling on a failed relationship and being chased by a lion can trigger the rapid mobilisation of energy from storage sites (e.g. fat cells, liver, muscles) and the inhibition of further storage — a hallmark of stress-response. So, what does this mean?
Cortisol, a steroid hormone produced in the adrenal glands located on top of the kidneys, is released as a short-term adaptive solution to mobilise energy reserves (e.g. glycogen) Once there is enough energy converted into glucose, critical muscles (e.g. the legs to enable running form any threat) receive it as quickly as possible. The mobilisation process receives additional support by an increase in heart rate, blood pressure and breathing rate, all of which circulate nutrients and oxygen. So far, so good, right?
However, remember that the brain controls the allostatic mechanism and does not distinguish what sort of emergency the body goes through (why? read here). The brain assumes there is a threat and reallocates its energy accordingly. In other words, whichever area or organ is vital to keep you alive (at that very moment) will receive energy; otherwise, it will have to wait until there is no more threat. Psychological stressors, however, might take a long time to go away.
Therefore, the brain maintains a state of emergency and halts most long-term and energetically expensive body functions. For example, during stress, there is reduced tissue repair and no digestive process available. Imagine a stranger attacking you. There is no need to have your digestive system functioning as if you were about to have lunch. Honestly? What you want is energy redirected to your legs so you can run away as quick as possible. These shifts also explain why in emergency situations your vision gets heightened, whereas your bowel movements may hint you need to go to the bathroom—immediately!
Likewise, the sexual drive undergoes some changes (e.g. females are less likely to ovulate, whereas males have difficulty with erection). The bottom line shows there is nothing more important than survival, and psychological stress creates unrealistic threats for long periods.
What is your weekly routine? Make a list of potential psychological stressors affecting you. How long have theses stressors been around? Have you noticed any symptoms of anxiety, such as excessive worry and difficulty to sleep?
Stress is a complex topic and has been negatively affecting many people’s physiology and mental health. It is a crucial survival mechanism linked to the brain, which controls the allostatic balance and will do whatever it is necessary to keep you alive. However, psychological stressors may extend for long periods and eventually affect essential body functions. The brain continually prioritises and reallocates energy to ensure survival. Similarly, if you unexpectedly lost your job, then you would save money for food and mortgage, rather than spending on a fancy dinner (presumably!).
 Sapolsky, R. M. (2004). Why zebras don’t get ulcers.
Subscribe for more content on Neuroscience & Stress.