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Using The DUTCH Cortisol Awakening Response (CAR) Test in Clinic: 101

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Using The DUTCH Cortisol Awakening Response (CAR) Test in Clinic: 101

According to the American Institute of Stress, 55% of adults report being stressed. Fatigue, characterized by a lack of energy, is one of the most common complaints evaluated at doctor's offices. The Cortisol Awakening Response (CAR) is a biological process that may give insight into how stress can impact energy levels.

This article will discuss the CAR, the Precision Analytical CAR test, who it would be appropriate for, and what to do regarding the results.


What is a Cortisol Awakening Response?

Our bodies have a 24-hour sleep-wake cycle called the circadian rhythm. The CAR is a main part of the circadian rhythm, as it is the main phase of our circadian rhythm in the morning. The CAR typically lasts 30 minutes after waking and is marked by a peak in a hormone called cortisol, where levels will increase by 50-160%. The CAR is primarily dependent upon light. When light hits our eyes, the light waves travel to a center in the brain called the suprachiasmatic nucleus (SCM). The SCM tells the rest of our body that it's waking time, initiating a cascade of various processes, one being cortisol production in the adrenal glands. After the CAR, cortisol levels should steadily decline throughout the rest of the day, with its lowest production at night. When cortisol is low, our nighttime hormone melatonin can be released, as they work inversely.

The Hypothalamic Pituitary Adrenal (HPA) axis may significantly impact the CAR. The HPA axis is activated when we undergo stress, whether it be physical, mental, or emotional. When stress occurs, a center in our brain called the hypothalamus senses it, releasing a hormone to the pituitary gland alerting it that our body is under stress. In response, the pituitary gland releases another hormone to the adrenal glands, telling them to release cortisol. In this capacity, cortisol induces various metabolic processes that aid in combating stress, including blood sugar release and inflammatory marker modulation.

Acute HPA axis activation is normal and will not affect the CAR. However, under chronic stress, the HPA axis is continually activated, leading to the perpetual release of cortisol. This, in turn, can lead to either an elevation of the CAR or depression, causing symptoms and possibly leading to certain health conditions.

What is The DUTCH Cortisol Awakening Response (CAR) Test?

The Precision Analytics (DUTCH) CAR test assesses cortisol and cortisone levels upon waking, 30 and 60 minutes after waking, in the afternoon, and at night.

While the CAR should take place within 30 minutes of waking, it can be delayed in some individuals, which is why the 60-minute measurement is there. The DUTCH CAR test also checks afternoon and night cortisol levels to view the circadian rhythm comprehensively. The CAR can influence cortisol levels throughout the day and vice versa.

In addition, cortisone levels are measured. Cortisone is the inactive form of cortisol, and it can convert back and forth depending on where they are in the body and what the body needs. During times of high stress, the body may convert cortisol into cortisone as a compensatory mechanism to control the effects of cortisol, such as high blood pressure and blood sugar. Cortisol levels may depress at a particular time in chronic stress, and this may cause more cortisone to convert into cortisol. There are many possibilities concerning cortisone and cortisol levels throughout the day. That's why it's imperative to gather a detailed patient history about stress and the timeline or duration of stress to interpret the results and formulate an appropriate treatment plan properly.  

When to Consider The DUTCH Cortisol Awakening Response (CAR) Test

The DUTCH CAR test may be helpful for people with the following symptoms and conditions:

  • Chronic stress
  • Chronic fatigue
  • Poor sleep, including sleep apnea
  • Migraines
  • Joint pain
  • High blood pressure
  • Autoimmune conditions
  • Depression
  • Seasonal Affective Disorder (SAD)
  • Blood sugar issues
  • Gut problems

How to Balance the Cortisol Awakening Response


Avoiding caffeine late in the day can aid in a healthy circadian rhythm. Caffeine can increase cortisol levels, and having caffeine in the late afternoon or evening can cause an increase in cortisol levels right when cortisol should be approaching its lowest concentration. This, in turn, can cause the entire circadian rhythm to be thrown off, affecting the CAR.

Morning Light

A study published in the Journal of Clinical Endocrinology and Metabolism showed getting light in the morning can help to increase cortisol release by up to 50%. Light at night will also cause cortisol production when it should be at its lowest, as nighttime is one of the times cortisol is most sensitive to light. Common sources of nighttime light include phones, tablets, and TVs; avoiding these electronics at least two hours before bedtime is advised for a healthy CAR and circadian rhythm. Ensuring your bedroom is as dark as possible will also support a healthy CAR.

In addition, having a consistent routine can also aid in a healthy CAR. Waking up and going to bed at the same time every day can help maintain a healthy cortisol rhythm.


Adaptogens are botanicals that can aid in the body's response to stress. Botanicas, such as Schizandra, Rhodiola, and Eleuthero, can modulate cortisol levels, aiding in a healthy CAR. However, the timing of supplementation is important and should be done upon waking to affect cortisol levels properly.

Another adaptogen may be effective in healthy cortisol levels. Ashwagandha, a traditional Aryuvedic herb, improved cortisol levels while enhancing cognition and feelings of happiness in a randomized control trial of 125 people.


The CAR is an important biomarker of health, as it is a part of our circadian rhythm and is influenced by the HPA axis. Understanding the stress level, including duration and severity, is essential to interpreting the CAR. Once the CAR is interpreted, a comprehensive treatment plan can be formed using evidence-based dietary, lifestyle, and supplemental support.

The information provided is not intended to be a substitute for professional medical advice. Always consult with your doctor or other qualified healthcare provider before taking any dietary supplement or making any changes to your diet or exercise routine.
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