Effects of stress on the body

Your ‘fight or flight’ response

When you’re faced with a stressful situation, your body goes into what’s known as ‘fight or flight’ – a human response to potential danger where the body gets ready so you can physically defend yourself or run away.

When this happens, your brain sends signals to your body to release hormones such as adrenaline and cortisol. These chemical messengers enter your blood and temporarily increase your blood sugar, blood pressure and cholesterol levels, and your heart rate.

In the short term, these changes help more energy and oxygen get to your brain and muscles, so you’re more mentally alert and physically prepared. Even your blood changes: it becomes more likely to clot, stopping you from bleeding too much if you were to be injured.

This ‘fight or flight’ response evolved to help our ancestors survive sudden dangers such as wild animals. And there are still some scenarios today when stress, and the effects it has on our body, can be useful.

For example, it’s helpful for your brain and body to be prepared when you’re about to take an exam, need to meet a tight work deadline, run a race, do an important talk in front of others, or face a situation where you might be physically harmed.

So, in the short term, stress can be helpful. However, if this ‘fight or flight’ stress response keeps being switched on again and again, over time this can take its toll on the body.

This type of chronic stress can happen for many reasons such as work, financial difficulties, family life or loneliness.

It can leave us with emotional and physical symptoms such as feeling easily angry, upset or worried, or having headaches, odd pains and trouble sleeping.

Is stress linked to heart disease?

Since the release of stress hormones affects the heart and circulatory system by increasing your heart rate and blood pressure, people often wonder whether stress can lead to heart problems.

More research is needed to be able to better answer this. But what we can say is that there is a link between the two.

2017 research on the effects of stress, part-funded by British Heart Foundation (BHF), reviewed many of the largest studies that have looked at how stress affects the heart. This involved data from hundreds of thousands of people.

Published in the journal Nature, it showed that adults experiencing stress at work or in their private life have a small increased risk of coronary heart disease and stroke. It also suggested that for people who already have heart and circulatory diseases, stress is linked with worse outcomes.

What is less clear is whether, and in what ways, stress might cause a greater risk of heart and circulatory diseases.

Some early lab-based studies on stress and cardiovascular disease are beginning to suggest that stress triggered changes to blood flow and inflammation could be responsible for an increased risk.

For example, a study in mice, part-funded by BHF and published by the European Heart Journal in 2021, reported that stress hormones lead to inflammation in blood vessels, particularly in areas of fatty deposits that can lead to coronary heart disease. But we need more real-life studies to fully understand this.

Stress and unhealthy habits

What we do know for certain is that stress can make us more likely to turn to unhealthy habits such as smoking, drinking too much alcohol, overeating and eating too much food that is high in salt, sugar and saturated fats, and being less physically active.

These ways of dealing with stress can lead to high cholesterol levels, high blood pressure and type 2 diabetes, which increase your risk of heart and circulatory diseases.

While it might not be possible to remove sources of stress from our lives, the good news is that there are things we can do to improve how we respond to them and how we feel.

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