What Causes Anxiety?

Anxiety is an emotion that involves a specific set of hormones or “signals” such as adrenaline within the body. It is the body’s natural response to danger or fear. This can be caused by the following:

  • Over-activity in the areas of the brain involved with emotions and behaviour.
  • An imbalance of serotonin and noradrenaline which help to control and regulate mood.
  • Disordered thinking.
  • Life Stressors. This can include things like work, relationships and finances.
  • Trauma, abuse, bereavement.
  • Health Issues such as pain and chronic conditions.
  • Upcoming events like tests and exams.

When the body is ‘stressed’ the brain sends out a distress signal. This activates:

  1. the sympathetic nervous system
  2. the flight / flight response (production of adrenaline and cortisol)

Adrenaline increases your heart rate, elevates your blood pressure and boosts energy supplies
Cortisol, the primary dress hormone, increases sugars (glucose) in the bloodstream, enhances your brain’s use of glucose and increases the availability of substances that repair tissues.

The Autonomic Nervous System

The Autonomic nervous system controls functions in the body like breathing, heart rate, digestion and many other things. It is a key player in the production and regulation of stress in the body. 

Activation of the parasympathetic nervous system allows the body to relax and digest food. This happens when you are calm and do not feel threatened. 

When the body is ‘stressed’ the brain sends out a distress signal which activates the sympathetic nervous system and leads to a fight or flight response (production of Adrenaline and Cortisol). This leads to an increase in heart rate, blood pressure and energy availability within your body.

The polyvagal theory suggests that trauma or PTSD can lead to exaggerated stress responses and chronic overactivity in the sympathetic nervous system.


Tells the brain all is well

Relaxed response

Activated by Calm



The brain’s distress signal

Involuntary Danger / Stress Response

Activated by Anxiety / Fear

Polyvagal Theory

When our environment feels safe and calm our body state is regulated efficiently (parasympathetic state)

When our mind detects danger or threat (real or perceived) this puts the body into ‘flight or flight’ mode (stress response)

When you experience trauma or PTSD, this can lead to a continued and exaggerated stress response (sympathetic state)

What is a Fight or Flight Response?

A fight or flight response is a natural bodily response to danger, fear or stress, like an automatic alarm system which prepares your body for action so it can respond quickly if necessary. Fears, phobias and irrational thinking can falsely trigger this response if they are perceived as a threat, which leads to physical symptoms.

  • Energy (Adrenaline) is rushed from the adrenal glands into the bloodstream to signal to large muscle groups that they need to be ready to either flee or fight.
  • Cortisol (Stress Hormone), is released into the bloodstream which increases blood sugar (glucose) concentration to enhance brain activity.
  • This response causes rapid heart rate, increased blood pressure, dizziness, shallow breathing, sweating, hypervigilance.  They also curb bodily functions that are non-essential or harmful in a fight or flight situation such as digestion.
  • Helpful in truly threatening situations but a hindrance if activated falsely
  • Can take 20-60 minutes for body to return to normal


Fight or flight is a natural response to something that is mentally or physically scary.

Fears, phobias and irrational thinking can falsely trigger this response causing physical symptoms

It is triggered by the release of hormones that prepare your body to either stay and deal with the threat or to run away in order to stay safe. 

Neither response is bad!

When the brain perceives a threat, it activates the body’s “fight or flight” alarm system, and adrenaline is released into the blood from the adrenal glands. We experience uncomfortable feelings because the adrenaline makes the body systems speed up, diverting blood towards the big muscles, preparing us to attack (anger) or escape (anxiety).

It increases your heart rate, blood pressure, and breathing and once the threat has gone it takes between 20 and 60 minutes for the body to return to its baseline levels. 

There are physical signs of the fight or flight response, such as 

  • Dilated pupils
  • Pale or flushed skin
  • Rapid heart rate and breathing
  • Trembling
  • Cortisol also curbs functions that would be nonessential or harmful in a fight-or-flight situation.

Fight or flight plays a critical role in how we deal with stressful and potentially dangerous situations within our environments. By preparing your body for action, you are better prepared to perform under pressure which can be helpful and making it more likely that you will handle things effectively. 

Why does anxiety affect breathing?

When we anticipate stress we tend to hold our breath

Extra oxygen is sought by the body in order to supply muscles with maximum energy in order to ‘fight’ which causes over-breathing (or hyperventilation). 

Anxiety Resources