Cortisol – what it is and why it’s commonly called the stress hormone

stress hormone - cortisol
on Tue 7 Jan


Cortisol is a steroid hormone which is produced in your adrenal glands and transported within your circulatory system.  Our cortisol levels vary through the day but they’re generally higher when we wake and then fall towards the end of the day.


Almost every cell in the body has a cortisol receptor so cortisol is able to do many things to regulate your metabolism - including blood pressure and controlling salt and water balance.


In a Society which is increasingly aware of mental stress, you will probably have heard of cortisol as it’s popularly referred to as “the stress hormone


This is because it also prepares your body for a flight or fight response when it is on high alert. Cortisol does this by altering or shutting down some of your body’s functions in order to make it more efficient at a time of crisis.


How is the release of cortisol triggered?

We have an emotional processor in our brain called the Amygdala and it’s this which will initially send out an “emergency distress signal” to your hypothalamus when there is a perceived crisis. In turn your hypothalamus releases what’s called corticotrophin-releasing hormone (CRH) which causes the pituitary gland to secrete adrenocorticotropic hormone (ACTH).  It‘s the higher levels of ACTH which are detected by the adrenal gland which is then stimulated to secrete cortisol. 


Your body is now preparing itself for its best chances of survival,  this includes having to decide whether to run away or square up to  the stressor. At this point the increased levels of cortisol will do several things, it will:


  • flood your body with glucose as a source of energy to your large muscles
  • inhibit the production of insulin in order to make the body’s glucose ready for immediate use rather than storing it in the body
  • Narrow your arteries to work in conjunction with adrenaline so that your heart beats more quickly and your blood is pumped harder and faster around the body
  • shut down functions which may slow down the body such as your digestive and reproductive systems
  • trigger an anti -inflammatory response to ready the body for recovery from injury or infection


Once the crisis is over your body’s hormone levels return to normal.  It does this via something called a negative feedback loop whereby high levels of cortisol block the hormones released by the hypothalamus and the pituitary gland.


So far so efficient – and amazing!


What happens if we are constantly stressed?

There is a theory that our fast pace of life keeps cortisol levels on high and this then has negative effects


  • The body can stay in an insulin resistant state which means that your blood cells are starved of energy and send hunger signals to the brain which make you eat more and put on weight
  • Stored body fat in the form of triglycerides is mobilised by cortisol to relocate into the visceral fat cells in the abdomen giving you the classic “spare tyre”
  • The body continues to produce more glucose than necessary leading to raised blood sugar levels and increasing your risk of type 2 diabetes.
  • Your digestive and reproductive systems can struggle with the ongoing negative effect of cortisol preventing them from working efficiently.
  • Your circulatory system is overworked.


Obviously this can cause serious health challenges.


Why people react differently to stress

As we know, the effect of stress varies from situation to situation and from person to person. 


There  is ongoing research about this including one interesting study which looked at whether stressful conditions in childhood and adolescence has  ongoing immunological consequences and how we are less able to mount the appropriate response to stress as we age.


You may want to read about this here 


Can my cortisol levels be checked?

A urine or saliva cortisol profile test are not well-accepted indicators of cortisol levels. A 9am blood test for cortisol preferably combined with measurement of ACTH is the best way to assess the adrenal gland. Occasionally a dynamic test called a short Synacthen test may be required.


Tests need to be interpreted by a trained professional as many factors can affect these including:

  • Your age and sex
  • Your menstrual cycle
  • An elevated cortisol is found in women on oestrogen therapy due to increased cortisol-binding globulin (CBG)
  • If you are pregnant or breastfeeding.
  • Your consumption of alcohol, cigarettes and caffeine
  • Medical conditions such as Addison’s disease or Cushing’s Disease


How can you reduce your high cortisol levels?

If your cortisol levels are high you might look at areas of your life where you could make a positive impact.

  • Try to sleep better as sleep deprivation will boost cortisol levels.
  • Drink more water as rising cortisol levels are triggered by dehydration
  • Are there ways you could better manage your stress by recognising the triggers and proactively managing these?
  • Make sure you’re not overdoing intense exercise as this triggers cortisol into coping with the extra stress you are putting on the body


I hope this has been helpful. If you would like to know about our other important hormones you might enjoy this blog post


Although every effort is made to ensure that all health advice on this website is accurate and up to date it is for information purposes and should not replace a visit to your doctor or health care professional.


As the advice is general in nature rather than specific to individuals Dr Vanderpump cannot accept any liability for actions arising from its use nor can he be held responsible for the content of any pages referenced by an external link


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