Stress, fear, and anxiety

Stress, fear, and anxiety


The Fight or Flight Response 

Anxiety, fear, and stress all activate our body’s stress response, also called the ‘Fight or Flight’ response. This causes several physiological changes to help us respond to danger or a threat. These changes prime your body to fight or flee the danger; and in some cases, there is a freeze response (think of a deer frozen in the headlights of an oncoming car). Some of the changes include:

  • Stress hormones (such as cortisol and adrenalin) are released- these are the chemical messengers driving physiological changes in your body, and they also help increase your energy level
  • Attention narrows to focus on the danger
  • Breathing becomes faster and shallower, to increase the amount of oxygen in the body
  • Liver releases sugar, providing fuel for muscles
  • Heart rate and blood pressure increase, to spread blood and oxygen around the body faster (giving muscles more fuel)
  • Muscles get tense and ready for action, for rapid responses (this can involve shaking)
  • Sweating increases, allowing the body to cool itself faster
  • Blood clotting factor increases, preparing for potential injury
  • Non-essential functions slow down, such as digesting food, producing saliva, and immune system functioning. This helps conserve energy and explains why you can have a dry mouth or tummy discomfort (including nausea or loss of appetite).

After the danger or threat is over, functioning and hormone levels return to normal. The fight/flight response is an evolutionary response that helps us survive dangerous situations. For example, imagine you are crossing the road. You suddenly notice a car speeding towards you- all of the above changes would occur in your body to help you get to safety by moving as fast as possible out of harms’ way. In the short term, this response can be life-saving.



Fear is an emotion that occurs in response to a significant danger and helps to keep us safe. It lasts as long as the threat does, and fades after this. In the above example of a car coming towards you, you would be afraid (and for excellent reason!), and this fear and activation of your fight/flight response would help you escape the danger. After having escaped, your body would begin settling down, and the acute fear would subside. Fear is therefore adaptive, helpful, and can be life-saving.



Anxiety is a reaction to a perceived threat (like fear), but it is a mood state which tends to persist long after any threat has gone. Anxiety tends to be out of proportion to the situation- you feel scared or worried even when there is no actual danger or threat. It can also involve apprehension: anticipatory worry or anxiety about something that has not happened yet. Apprehension is often focused on a vague or imagined threat- such as worrying about how you’ll perform at public speaking and assuming the worst: that you’ll make a fool of yourself and be judged negatively by your peers.

Anxiety keeps the fight or flight response activated in the long term, which produces a range of difficulties over time: for example, stress hormones keep you awake (to respond to danger), causing insomnia. Longer-term suppression of your immune system means you are more susceptible to bugs, and you may feel chronically unwell. Fight/flight narrows your attention to focus on a threat (or threats), making it hard to concentrate on anything else or to think clearly. The symptoms of anxiety can feel uncontrollable, cause distress, and interfere with your day to day life. As anxiety is impairing, it does not help you respond to the threats that made you anxious in the first place. For example: worrying about making the right or wrong decision can cause indecision and lead to avoiding making a decision altogether or leaving it until crunch time. Chronic activation of fight/flight as a result of anxiety is therefore unhelpful.



Stress is a perception that the demands or pressure placed on us are greater than our resources or ability to respond. Stress is a part of daily life, and sources of stress are called stressors. These also activate the fight or flight response. When the stressor resolves, so does your body’s stress response- which makes it different from anxiety.

It is important to note that stress can also be positive. For example, when you have that work deadline looming, getting tense and focused on the threat (i.e., completing/not completing the task in time), to a reasonable degree, actually improves performance and achievement, making it more likely you will achieve that deadline. It is when you are overwhelmed by stress that your performance deteriorates; for example, when you have multiple stressors occurring at once with no way to achieve or resolve any of them. This can lead to impaired concentration or focus, difficulty thinking, and feeling overwhelmed, in which case your fight/flight response doesn’t help you rise to the demands present. When stressors are ongoing and cannot be resolved, then fight/flight is chronically activated and can cause constant stress, lack of sleep, fatigue, impaired concentration and coping, which does not help you to perform well.

Activation of fight/flight in response to stressors can be helpful or unhelpful, depending on the degree and duration of stress, and nature of the stressors.



Anxiety, fear, and stress can all feel similar as they activate the same fight/flight response. In the case of fear, behaviour is organised in a helpful and adaptive way to respond to a real and acute threat. Regarding anxiety, the fight/flight response causes impairment in day to day functioning and is therefore unhelpful. In the case of stress, the fight/flight response can either be helpful or unhelpful to help us rise to the demands of our stressors. Unhelpful versus helpful activation of fight/flight in response to stress depends on the degree, duration, and nature of the stress.




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