By Liam Mannix
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We seem to accept stress as a part of our lives, sometimes even wear it as a badge of honour – “look how important and busy my life is”.
Mobile phone notifications and emails from the boss create a stress response when there is no real threat.Credit: Getty Images
But there is strong evidence chronic stress is bad for us – for some diseases, it poses risks comparable with inactivity.
After spending a few months speaking to researchers about stress, I’ve come to view it as our inherited superpower, bequeathed by hundreds of millions of years of evolution. It makes us stronger, faster and smarter.
But it is an extremely poor match for a modern life crowded with the stress of phone notifications, social media and after-hours emails from our bosses.
“In the modern context, what we now see is this chronic elevation of our stress response, in an environment that does not offer the same threat,” says Dr Joshua Hendrikse, a neuroscientist at Monash University who studies the effects of exercise on brain health. “The same pathways are active.”
A deeply evolved superpower …
You can tell how important the stress system is by looking at how deeply rooted it is within the tree of life. Stress responses are universal across organisms – from yeast and oysters to peanut-trees and humans. Different organisms use different molecules, but the shape of the response is largely the same: a sharp peak followed by a slow recovery.
Evolution selects for adaptations that make an organism more likely to survive and reproduce. The stress response enables organisms to mobilise all of their energy against a threat.
A cave woman spots a tiger: her body quickly mobilises all her resources to either fight or flee, giving her the best possible chance to survive.
How?
In humans, the stress response has two axes: the brain and the hormonal system. The brain, running at the speed of thought, is quickest off the mark. The sympathetic nervous system triggers the release of neurotransmitters which speed up heart rate and breathing, and decrease blood flow to the periphery – giving our organs more energy to work with. Other systems, now extraneous, slow down.
This system also dramatically sharpens our cognitive abilities. When researchers tested volunteers on a dice game requiring quick and precise calculations of risk, their score almost tripled five minutes after encountering a stressful situation (in this case, a fake job interview).
Meanwhile, our hormonal system is working to dump cortisol into our bloodstream. This hormone takes a few minutes to circulate, but when it does, it kick-starts the breakdown of stored fat and protein into energy, and initiates glucose production in the liver. Our system is hit with a big surge of energy – very useful for fight or flight.
… and a double-edged sword
If our stress reaction makes us smarter and stronger, why not keep it running all the time?
Organisms need to do a lot of energy-intensive things to pass on their genes, such as hunting for food or mating. When the stress system is active, these other systems are down-regulated. Short-term suppression is useful, but suppressing a key system for too long can be harmful. You don’t want to suppress the reproductive system indefinitely, for example.
And chronic stress poses a second risk: our bodies seem able to handle only a certain amount of stress activation before damage starts to accumulate.
This theory is known as allostatic load. If we are exposed to short bouts of stress we can handle – the occasional tiger – the cycle of stress and recovery helps us grow stronger over time. Indeed, stress seems to enhance our ability to form memories, perhaps so we can remember not to go back in that cave where the tiger was.
But if the stress is chronic, we do not get a chance to recover, and our allostatic load increases.
The big problem is we now live lives where we are constantly exposed to stress – from our jobs, from our technologies, from life.
The stress response elevates our blood pressure to force nutrients and oxygen into the muscles and organs. But leaving this system activated too long promotes cholesterol build-up on our artery walls. Stress mobilises energy; chronic stress messes with our insulin sensitivity and promotes obesity.
In the brain, stress fires up our memory – that’s why we can remember, in almost-perfect detail, our most-stressful moments (like childbirth). But chronic stress causes the atrophy and eventual death of neurons, increasing the risk of mental illness.
People exposed to chronic stress even seem to have shorter telomeres – a sign of accelerated ageing.
What we can do
I want to highlight two different approaches to dealing with the stress of modern life that are very different but, I think, complementary.
The first approach is mindfulness meditation. High-quality evidence suggests it reduces psychological distress by a small to moderate amount, and that effect seems to last.
Why? Probably because mindfulness teaches us to distance ourselves from the thoughts and emotions that are causing us stress, says Dr Julieta Galante, deputy director of Melbourne University’s Contemplative Studies Centre.
“Find [a mindfulness meditation class], if you can, that’s led by a teacher in a group setting. That’s the one we have the most evidence for.”
The second approach is to accept stress as a part of modern life and try to build resilience to it. You can do this by giving yourself small doses of stress via exercise.
“Exercise, in the short term, ramps up our stress response and increases cortisol. But if we habitually engage in exercise, the evidence suggests you get an adaptive response,” says Monash University’s Joshua Hendrikse.
“You’re building an adaptive, positive resilience. A short-term stressor for longer-term down regulation and normalisation of this system.”
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