Understanding the Fight or Flight Response
Most of us have heard of the fight or flight response, we have all experienced it and
can probably name some of the physical symptoms that occur with it but many of us
don’t understand the reason for the symptoms which makes the whole experience
feel scary and overwhelming. When we understand exactly what is going on and
why, the experience takes on a different perspective, and we can see how brilliant
our bodies actually are.
The fight/flight response is our body’s way of protecting us from danger and is part of
the sympathetic nervous system. To understand the adaptive function of this
response we need to remember that this part of our nervous system developed
around 400 million years ago as a survival mechanism. It is designed to mobilise our
body to either run from or fight a predator.
Now 400 million years ago animals needed this response to deal with threats to their
physical safety. Fight/flight was designed to be a short acting physical response that
settled once the danger had passed. In our lives today we still face the occasional
physical threat such as when we are crossing the road and a car comes speeding
towards us or if a big dog lunges at us, but the majority of the time this response is
triggered by a whole host of modern-day stressors, worries and situations that
generally don’t pose a physical threat. When we run across the road to avoid being
hit by a car, we experience the same symptoms but we physically move to respond
to the threat, we understand why our heart is beating fast or our breathing is shallow
and after a short time it settles because the danger has passed. When faced with
“threats” that don’t directly impact our physical safety or require mobilisation of our
body, the impact is experienced differently, as anxiety, panic, hypervigilance and
stress.
Let’s have a look at what the actual physical experience of fight/flight involves and
why every symptom makes perfect sense if you understand it from an evolutionary
perspective, from the perspective that your body is preparing to run away from (or
fight) a tiger. Knowing this information won’t change the physical experience, but it
can make a difference to how scared or overwhelmed you feel when it happens and
how you learn to manage it.
Imagine I asked you to sprint around the block. Most people would come back with their hearts beating fast, breathing rapidly and probably a bit sweaty. Why? The answer is not “because I am unfit”. Your heart would be beating hard and fast to pump blood around to your big muscles in your legs and arms that were needed for sprinting. Your breathing would be rapid and shallow to take in more oxygen to oxygenate the blood that is being pumped to your muscles, and you would be sweating to cool yourself down. When we go into flight/flight mode these physical changes happen for the exact same reason. If you are going to run away from (or fight off) a tiger, then you need oxygenated blood to be pumping to those big muscles. The heat produced by this will cause you to sweat to cool your system down. Another advantage of sweating is that if a predator tried to grab you, you would be slippery and harder to hold on to!
Remember when you were a child and were told not to go swimming straight after you ate? Would you eat a meal and then go for a run? Why not? Our digestive system uses a lot of blood and energy to digest our food, hence the need for a nap after a big meal. When we move into flight/fight all the systems that are not essential to survival shut down. When our digestive system shuts down, we get that feeling of nausea, butterflies or knot in our stomach. Saliva production ceases too as it is not essential for survival, so we experience a dry mouth.
Facing a tiger when we are relaxed is unlikely to end well. Our muscles tense so we are ready for action.
We have all experienced pins and needles in our foot if we have been sitting on it for too long. This occurs because the blood flow to that area is reduced. If we need to run away from or fight a tiger, we need the blood to be moved to those big muscles in our legs and arms. This means blood moves away from our extremities which sometimes results in pins and needles. Another additional benefit is that if you are fighting a predator, the most likely place you will get cut is on an extremity and if there is less blood flow you are less likely to bleed to death – not so helpful if you are dealing with a stressful life event but very helpful if you are fighting a tiger!
Our pupils dilate to let more light in to improve your ability to spot the danger. Anyone who has ever left a dark room or a nightclub after the sun has risen will remember those few moments where their pupils were still dilated from the dark and needed time to adjust to the light.
When our brain signals danger our prefrontal cortex, our thinking brain, goes offline. This is helpful if we are faced with a tiger because the last thing we want to do is stop and have a think about the best course of action. We want to react on animal instinct which is more likely to keep us safe. A tiger isn’t going to wait for you to decide what to do. This is great if there is an actual danger but not so helpful if we are faced with situations that require logical thought and problem solving.
A quick note about the freeze response which is linked to fight/flight. Freeze is also a brilliant survival strategy that happens instinctively. It can be thought of as “don’t move or else you will die” or a state of immobility when neither fight or flight will be helpful at that point. It is a state of hyperarousal like fight and flight. This is not the same as shut down (which is a state of hypoarousal) although many people confuse the two. Think about a wildlife documentary where a deer is being stalked by a lion. When the deer notices the lion, it freezes which hopefully results in the lion losing interest and moving on to find other prey.
So, when we understand exactly what our body is doing and why, we can stop fearing these experiences and start to say, “thank you body for protecting me even though it is not actually needed right now”. Using breathing, grounding or other somatic strategies can help send a message to our brain to say “there is no tiger, I am ok” which can bring our thinking brain back online and start to settle the physical sensations.
Our bodies really are incredible in this way. And remember, it would be ridiculous to have an inbuilt protection mechanism that harmed us. When the fight/flight response is acute and settles once the danger has passed then it is perfectly safe. It is when we experience this state for prolonged periods due to ongoing stressors that it can become harmful. That is when it is really important to seek support to develop strategies to calm our nervous system and bring our thinking brain online to be able to manage whatever situation life is throwing at us.
