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Is Stress Good Or Bad? (Answer: Both, But When & How?)

Chances are you know someone who messed up a job interview or failed a driving test because they got stressed, got flustered, couldn't focus or think straight, froze up or otherwise fell to pieces. Maybe it even happened to you. So it's easy to see how stress can seem like a threat to be avoided – it can harm your performance and even your health (there's plenty of research linking stress to ill-health).

Yet there's also the idea of “good stress”, known in psychology as “eustress”. Some stress can actually benefit you. Here's an example: researchers measured the stress response in a group of people about to take an exam. More specifically they measured the rise in the stress hormone cortisol. They wanted to see what effect the size of the stress response had on exam performance. You may be surprised to learn those people showing a larger rise in cortisol did better in the exam.

There's another way stress can be good for you: it may be a form of hormetic stress. Hormesis refers to a biological process whereby a short-term negative impact turns into a longer term benefit. An example of hormetic stress is weight-lifting. In the short term it causes microscopic damage to your muscle fibres. In the longer term, the body is stimulated to repair the damage, plus some. The result is greater strength and fitness, and in some sense this is true for other forms of stress including psychological or emotional stress. In some way the brain or nervous system is fitter and more adaptive. For example, through experiencing stress you've exercised the "muscle" of your relaxation response.

So it does seem that stress can be both helpful and harmful. The question then is, how and when?

Three Ways Stress Can Be Harmful

1. When it becomes chronic

The biological stress response is designed to be short-term. A zebra runs away from a lion, then relaxes back to baseline. There's a temporary mobilisation of energy, and diversion of resources towards fight or flight and away from processes like digestion. We would do the same, for short term stressors, but if you're worried about paying your mortgage, or your weight, or your child being bullied, then thoughts can nag away at you all day, and day after day. Then the same biological processes that are helpful in the short term can get locked in, and so become harmful.

Take the stress hormone cortisol. In the short term it can raise your blood sugar, giving you more energy. But chronically elevated cortisol can damage and even kill brain cells. (And having chronically raised blood sugar isn't too great either.)

When a body response gets stuck, you can lose self-regulation, which is your capacity to adjust biological parameters to most appropriately meet the challenges of the moment. There's evidence that chronic stress sufferers lose this adaptive capacity.

2. Extreme stress leading to trauma

If it's extreme, even a single episode of stress can lead to a locked in response, and a diagnosis of PTSD (Post-Traumatic Stress Disorder).

Interestingly, not everyone who experiences extreme stress goes on to develop PTSD. It seems you can be more or less vulnerable to PTSD, depending on a number of factors but including the level of your stress resilience skills.

3 When you believe stress is harmful

This is perhaps the most interesting and surprising of the three. Psychologist Kelly McGonigal presents evidence that believing stress is harmful is a self-fulfilling prophecy in her popular TED talk:

Why should this be so?

If you believe stress is harmful, you'll likely adopt an avoidant strategy. When stress happens (as it inevitably will) probably resistance will arise (this is a mindset of trying to reject a feeling – the problem is, it is itself a trigger for more fight-or-flight, thus amplifying the stress response). Moreover, you're in danger of getting locked into a chain reaction, never really relaxing, and risking turning everyday stress into chronic stress. (In other articles I've called this the "quicksand trap".)


I hope you can get a sense of the importance of developing (i) a positive stress mindset where you embrace stress as a positive challenge, confident of your ability to calm down afterwards, and (ii) stress resilience skills – resilience is the ability to recover quickly and easily from stress, upsets and set-backs.

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