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The fight or flight response explained

| APR 8, 2020

Due to the unforeseen and challenging situation we have found ourselves in, many of my clients (and I’m sure this applies to numerous people out there too) are feeling stressed and worried. The majority of them feel anxious about being in lockdown, worried about their jobs, home schooling their children, financial uncertainty, their ability to exercise and buying food. Although they feel stressed, very few understand the physical and mental effects this has and how to deal with it. 

I hope this blog will give you a little insight into the mechanisms of stress in the body and provide a few helpful tips on how to manage it…

What happens when you’re stressed?

A stressful situation triggers the release of stress hormones that prepare the body for ‘fight or flight’. Responding to stress is a natural process and necessary for survival, but if the body senses stress over a long period of time it can have damaging effects mentally and physically.

How does it actually work?

When the brain detects stress, a signal is sent to the hypothalamus (part of the brain) which communicates with the rest of the body via the autonomic nervous system. This is made up of the sympathetic nervous system, also known as ‘fight or flight’, and the parasympathetic nervous system, also known as ‘rest and digest’.

A stressful situation triggers the hypothalamus to activate the sympathetic nervous system. This causes the adrenal glands (endocrine glands that sit above the kidneys) to release adrenaline into your blood. Circulating adrenaline causes numerous physiological changes preparing the body for ‘fight or flight’. These include: 

  • Increased blood pressure

  • Increased heart rate to ensure blood is pumped to muscles, heart and other vital organs

  • Widening of pupils

  • Sweating

  • More oxygen being sent to the brain to increase alertness

  • Sight, hearing and other senses become sharper

  • Suppression of the immune and digestive systems

If the brain senses continuous stress, the hypothalamus releases more hormones which eventually cause the adrenal glands to release cortisol, another stress hormone. This causes the body to stay on high alert until the threat has passed and cortisol levels fall. The parasympathetic nervous system then kicks in dampening the stress response. This  promotes the ‘rest and digest’ stage by decreasing your heart rate, increasing digestion and helping the body to calm down.

If you are continuously stressed, the levels of stress hormones remain high and your body may not be able to move into the ‘rest or digest’ phase which can lead to:

  • Fatigue

  • Headaches

  • Difficulty concentrating

  • Digestive problems

  • Changes in appetite

  • Difficulty sleeping

  • Lowered immune system

  • High blood pressure and heart rate

Ways to move from fight or flight to rest and digest

Below are a few tried and tested tips that both myself and my clients find incredibly useful to calm the mind and body down…

Deep breathing

Focusing on your breath can help reduce the feelings of tightness and tension in your chest and throughout your body. One particular technique that I (and many of my clients) find incredibly helpful is breathing in slowly for 4 counts, holding for 4 counts and breathing out for 5 counts. Repeating this a few times only takes a few minutes and can help your mind and body relax.

Distance yourself from screens

We are increasingly spending a large proportion of our days on technology. Endless scrolling and lack of movement can increase the risk of feeling permanently stressed out. Setting a time towards the end of the day to set your screens aside can give you time to wind down in the evening with no distractions. This allows you to spend a few hours doing something different every evening that you enjoy such as cooking, exercising or reading.

Gentle exercise

Activities such as a walk outside and gentle stretching or yoga are great tools for stress. Combining movement with breath work also works wonders for relieving tension. It’s also important to remember that over exercising can add to stress, especially if you aren’t eating a balanced diet. Listen to your body.

Eat a balanced diet

Eating a balanced diet with a wide range of fresh fruit and vegetables, complex carbohydrates, protein and healthy fats can help support your body.  With the necessary nutrients, your body can keep the adrenal glands and other systems in check whilst in distress.

Try to enjoy your meals seated with no distractions. Chewing your food thoroughly can help support digestion and relieve tension at mealtimes.

Limiting caffeine intake

Although this might be challenging when stuck at home, try to limit your caffeine intake to 1 coffee/tea per day. This is incredibly beneficial in reducing anxiety and stress symptoms. As caffeine has a half-life of 6 hours, substituting or avoiding any caffeinated drinks after 2pm for herbal teas can also improve sleep.


Making time for yourself and doing something you love, whether it is having a bath, going on a walk, reading or spending time with loved ones is vital for relieving stress. Even just a few minutes a day can provide time to recuperate and give your body a chance to slow down.


Set yourself a regular bedtime and aim for 7-9 hours of sleep per night. Avoid screens at least 2 hours before you go to bed, this really helps you wind down in the evenings and prepare you for a good night’s sleep.

Claudia Criswell is a Registered Nutritional Therapist with clinics in Edinburgh and London specialising in nutrition for gut health and mental health. Claudia focusses on helping her clients achieve their optimal health, with a healthy and happy relationship with food. You can find her on instagram @claudiacriswell_nutrition or her website

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