Ever watched a wildlife documentary where a seemingly peaceful looking herd of zebra are eating grass in the plains of Africa when suddenly from out of nowhere a cheetah attacks? Usually the scene that follows is very dramatic as the hunt unfolds and the herd are running for their lives.
The way the zebra's body reacts during intense moments like these gives it the very best chance of staying alive. A part of the brain known as the amygdala fires off the panic button, activating the zebra's sympathetic-nervous-system (SNS). The SNS is a series of processes in the zebra's body that help it survive.
For example, blood is pumped to its large muscle groups to help it run and energy is diverted away from digestion, reproductive organs and immune functioning, none of which will save the zebra from the short term threat of death. Chemicals are dumped into its bloodstream to help it run such as adrenaline and cortisol. It's a pretty impressive system and all going to plan the zebra escapes to eat grass for another day.
What happens then? It's quite incredible how quickly the zebra can calm down and be back to munching grass after almost being eaten! This is because the body switches on its parasympathetic-nervous-system (PNS), the bodies calming system, helping recovery after a big threat.
As humans, we have the same primitive threat alarm system. Which is not surprising really, given that for 2.6 million years we lived as primitive tribes and needed to be constantly alert to threats. It's only very recently (the last 12,000 years), that we've lived in more stable, settled societies, and thankfully most of us now don't have to be on constant watch for life threatening events.
However, the primitive part of our brain is still constantly scanning our environment looking for threat, on a hair trigger, ready to fire off the SNS with a mere hint of anything alarming. Our body will react the same way regardless of whether the threat is real or in our heads.
These days 'threats' come in the way of thoughts like "I'm not feeling prepared enough for this afternoon's presentation", "I'm never going to get through my to-do list", or "I think I'm going to miss my bus". Or feelings of worry, anxiousness, anger and frustration. This constant barrage of thoughts/feelings trigger our threat system affecting the functioning of things like digestion and our immune response, and dumping adrenaline and cortisol into the bloodstream. It's almost like it's keeping us constantly simmering these harmful chemicals.
The long terms effects of ongoing stress on our bodies has been well documented (American Psychological Association, n.d.). We know that ongoing chronic stress causes muscle tension, heart conditions, sleep problems, and problems with digestion to name a few.. Recent research also shows that chronic stress can speed-up the aging process by shortening the length of each DNA strand (Berglund, 2014a).
It's also important to understand how feelings of stress affect the brain. The ongoing production of chemicals such as cortisol are toxic to parts of the brain. Alarmingly, it can actually damage brain cells and prevent new ones from forming, which can prevent new learning from happening (Bergland, 2014b). Our amygdala can become overactive, which can leave us feeling anxious, nervous, stressed and even depressed, limiting our resilience and creativity (Chaskalson, 2011).
So knowing our own minds, being aware of unhelpful thoughts and feelings as they arise, can have a huge impact on our health. By doing this we can choose to respond more skilfully rather than reacting the way we might normally do.
Let's not forget of course that certain types of pressure are good for us and 'good stress' helps us achieve our goals. Long periods of chronic stress, though, can cause all sorts of problems, so we have to look for ways to activate the PNS system to allow our bodies time to calm, rest and switch off the panic button.