Fight or Flight – How our bodies respond to stress

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I was watching one of those nature shows with my 5 year-old daughter showing a peaceful scene of grazing zebras. The zebras began to swim across a river when suddenly a crocodile exploded out of the water and attacked a zebra. The zebra reacted with an adrenaline-fuelled surge and escaped onto the riverbank with only a gash on its hindquarters. The zebra exhibited a ‘fight or flight’ reaction in response to a life-threatening situation.

This is the same response that humans experience – acute stress reaction – when we perceive a significant threat or danger. Imagine the reaction of a soldier at a checkpoint in Iraq calmly watching a car driving down the road – then suddenly realizing that the car is rapidly accelerating directly towards him with no intention of stopping.

Physically, our bodies react to this stress by activating the sympathetic nervous system (SNS) which immediately releases hormones such as adrenaline and cortisol. This results in the liver producing more blood sugar/glucose which gives a short burst of energy, an increase in heart-rate and breathing, dilated blood vessels in the arms and legs, and tensing of the muscles in preparation for explosive activity. This adaptively prepares us for fight or flight. There are actually two other responses that are lesser known but also common – ‘freeze’ or ‘posture’. The soldier could shoot at the car (fight), run for cover (flight), be paralyzed by fear (freeze) or brandish his weapon in the hopes that the car will be deterred (posture). This is a very adaptive reaction when we are facing life-threatening situations like the soldier or the zebra.


“A man is as unhappy as he has convinced himself he is”



Fortunately we live in a relatively peaceful society and very few of us encounter true life-threatening situations on a regular basis – if at all. Interestingly, we sometimes activate our sympathetic nervous system when faced with lesser non-life threatening situations. Think about anxiety-provoking situations – e.g., public speaking, confronting a friend – during which you may have experienced a rapid heart-rate, difficulty breathing, ‘butterflies’ in the stomach, tense and trembling muscles and other symptoms. This was your nervous system mistakenly preparing you for a life-threatening physical altercation. In fact, some people keep their system constantly on high-alert – activating it repeatedly over minor stressors. Over time, this takes a toll and leads to symptoms of chronic stress – such as, tension and migraine headaches, problems with the digestive system, sexual dysfunction, and a greater long-term risk of heart attacks, depression, hypertension or stroke. The American Psychological Association website ( has an interactive model demonstrating how stress affects your physical health.

Fortunately, we can learn to manage this overreaction. You can experiment with two simple techniques. First, the next time you experience significant physical anxiety – you can rationally dispute the overreaction by reminding yourself that your nervous system reaction is there for life-threatening emergencies. Rate the level of the stressor on a scale of 1 to 10 – with 10 being life-threatening. If upon reassessing the situation you conclude that it should realistically be rated as a 3 – this revised perception will often result in decreased physical anxiety. Seneca, a Roman philosopher stated, “A man is as unhappy as he has convinced himself he is.” Finally, a simple and effective technique is diaphragmatic breathing. Take slow deep breaths by expanding the diaphragm – e.g., pushing the belly-button out when inhaling. This counteracts the physical anxiety by creating a relaxation response.

Dr. Martin Phillips-Hing is a registered psychologist (#1361) with a private practice at Oakhill Counselling and Mediation Services in Abbotsford.  Comments or questions can be sent to him via his website –

[Article published in the Abbotsford Post – November 10, 2006]

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