How stress affects your body and brain – and what to do about it

What does it really mean when we talk about stress? Clinical physiologist lead, Marcus Herbert, explains what’s going on inside your body and your brain when stress strikes

CREDIT: this edited version was first seen on Nuffield Health

Stress is a very personal matter in that it relies on our own perceptions. Put simply, stress is when a situation, pressure or change exceeds our coping abilities.

Take a rollercoaster ride for example. You might have two people who go on a rollercoaster together; one person may take genuine enjoyment from the experience while the other may experience genuine fear or anxiety. The rollercoaster itself doesn’t change, but our perceptions of it will differ; the same can be said for other stressful situations.

Of course, this example is just short-term stress which, in isolation, may not cause us any harm at all. It’s only when stress accumulates, and exceeds our coping ability without adequate recovery, that it becomes a problem. Stress is likely to occur after a build-up of life-change events that can be either positive or negative. These could include a business realignment, a promotion or even something enjoyable, such as a holiday. What matters is that there is a change to your normal routine.

We all know that stress can make us feel upset, agitated and, sometimes, overwhelmed. The question is how does stress affect our body and our mind, and what can we do about it?

The physiological effects of stress
Within your central nervous system (your brain and spine) you have the autonomic system; this controls all of the processes that you do without thinking, such as breathing, digestion and your heartbeat.

Within the autonomic system there are two systems of interest which work in tandem with each other. These are the sympathetic system, known as the ‘fight or flight’ system, and the parasympathetic system, or the ‘rest and digest’ system.

The sympathetic system is responsible for increasing heart rate, increasing blood pressure and increasing blood sugar to help you to perform when stress hits. When you are stressed this system triggers these necessary responses and the function of your rest and digest system is reduced. The parasympathetic system is responsible for suppressing heart rate and bringing you back down to homeostasis.

A hormone released when we are stressed is cortisol. Cortisol is an energising hormone which increases the level of blood sugar. This is great in the short term – providing energy to react quickly – but, in the long term, it can be bad for the immune system because DHEA, which is also released by the adrenal glands and supports our immune system, can’t be released when cortisol is released.

Excess release of cortisol over a long period of time can also lead to increased risk of strokes and heart attacks. When blood sugar levels are raised this can lead to inflammation of artery walls; this damage can cause the immune system to respond, leading to a build-up of fatty deposits which can block the arteries. If some of this build-up breaks away, and is released into the bloodstream, then it can block smaller arteries that lead into your brain or heart.

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Stress can also limit our ability to think clearly. When we are stressed our amygdala labels information coming into the brain as threatening and, at the same time, limits activity in the cerebral cortex – the part of our brain that allows us to think strategically. This reduces our ability to make decisions, be sociable and take on new ideas and information. As a result, you may act in a way that you might later regret.

Coping strategies
So how can we combat these effects of stress and learn to develop resilience and perform better under pressure? When it comes to effective stress management, it’s important to focus on the factors that are within our control.

1. Better sleep
Getting a good night’s sleep is important in reducing stress because, when we are deprived of sleep, the amygdala becomes much more reactive and so, too, will our minds and bodies. It’s also important to take regular breaks during the day to re-energise.

2. Gentle exercise
Low-to-moderate intensity exercise – with a focus on muscle activation and breathing, like yoga – can also have a positive effect on stress. This is because it drives up the activation of the rest and digest system, rather than the fight or flight system which is activated during more intense exercise; therefore, going for a gentle walk before bedtime can be more beneficial than a high-intensity run. Furthermore, exercise can be a welcome distraction from the stressors in your life.

3. Don’t look to substances to unwind
There are some lifestyle considerations that can help reduce stress too. Ingesting caffeine, alcohol and nicotine all increase the activation of the fight or flight system – so smoking and drinking wine are not the destressors that people think they are.

Taking these factors on board, and modifying your behaviour, can help you to improve your ability to prepare for, react to and recover from, the stressors in your life, ultimately improving your resilience.

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