Physiology Of Anxiety

Anxiety is part of what is called fight-or-flight response, which is generated by the sympathetic nervous system. The sympathetic nervous system along with the parasympathetic nervous system forms the autonomic nervous system. The actions from the autonomic nervous system are automatic and not under our conscious control.

The sympathetic nervous system activates the fight-or-flight response, while the parasympathetic nervous system restores the body to normal mode. While one is responsible to rev up, the other is responsible to hit the breaks.


The fight-or-flight response is a natural protection of the organism during a threat, which can be real or imaginary. We either go away from the threat or fight it. That is why some people who suffer from anxiety are very aggressive, while others run away in fear, during a threatening situation.

The physiology of fight-or-flight involves production of adrenaline and cortisone by the adrenal glands. These hormones cause:

• Quicker heartbeats, which results in more oxygen going to the muscles
• Faster breathing
• Sweating
• Less circulation of blood in the gastro-intestinal tract and skin and more circulation in the skeletal muscles and lungs
• Release of glucose from the liver to the bloodstream to give energy to the body to confront the threat
• Dilation of pupils

Cortisone inhibits the immune system, which reduces inflammation and pain. We can see that this is useful in case of physical danger (i.e. the organism that is injured can better face the threat with less pain).

Suppression of the immune system by cortisone is the probable reason why people that are usually stressed or anxious are more susceptible to sickness.

Because, adrenaline and cortisone take some time to be destroyed by the body, anxiety or discomfort is still present after the threatening situation. This delay for the elimination of these hormones is also for protection of the organism, just in case the threat comes back.

We can see that the fight-or-flight response exists for the body to physically act. This was most useful when humans had to hunt to survive. During this time, threats that required immediate and fast physical action, such as an attack by an animal, were more frequent.

In modern life, intense physical action is not what is needed most of the time during moments of anxiety, as for example, in stressful situations at work or school. Everybody faces situations that cause the fight-or-flight response. The problem is when this happens frequently due to psychological problem. In this case, if it is not controlled it can be harmful to ones health.

There are several approaches that can be used to reduce anxiety, such as, physical exercise, changes in life style (e.g. more rest time), cognitive-behavioral therapy, meditation, visualization, relaxation techniques, neuro-linguistic programming, and others. All these methods can be used for any type of anxiety. If combined together, the effect on the reduction of anxiety will probably be better.

The approach to be used will depend on what you believe will work for you. Try one and if it does not work, try another one. You will eventually find what works best for you.