The cortisol awakening response (CAR) profile by ZRT Laboratory offers a comprehensive assessment of cortisol levels at specific time points after waking, providing valuable insights into the body's stress response dynamics. Cortisol, often termed the "stress hormone," plays a crucial role in regulating various physiological processes, including metabolism, immune function, and the body's response to stressors. The CAR profile measures cortisol levels upon waking and at subsequent time points, allowing for the evaluation of the natural diurnal rhythm of cortisol secretion and the magnitude of the cortisol response to the morning awakening. This information can aid in assessing individual stress resilience, identifying abnormalities in cortisol secretion patterns, and guiding personalized interventions to optimize stress management and overall well-being.
Six salivary cortisol measurements are taken during a 24 hour period in the Cortisol Awakening Response Profile. These measurements allow for the assessment of the cortisol awakening response, which is the natural increase in cortisol levels that occurs within the first hour after waking. By evaluating cortisol levels at these time points, the CAR profile provides insights into the body's stress response dynamics and diurnal cortisol rhythm.
The test assesses the following cortisol measurements throughout a 24 hour period:
Cortisol level immediately upon waking (0 minutes post-waking)
Cortisol level approximately 30 minutes after waking
Cortisol level approximately 60 minutes after waking
Cortisol level before lunch
Cortisol level before dinner
Cortisol level at bedtime
This test also assesses salivary DHEAS levels, which is another biomarker of adrenal function. [2.]
In healthy individuals, cortisol is expected to rise in the morning by as much as 50%, peak approximately 30 minutes after waking, and fall back to morning waking levels within 60 minutes of waking [5.] . This is called the Cortisol Awakening Response, or CAR, and it provides valuable insight into the functioning of the HPA axis. [6.]
The Cortisol Awakening Response (CAR) is clinically relevant because it reflects HPA axis function, which is associated with various physiological and psychological factors. Research suggests that a robust CAR is indicative of healthy stress regulation and adaptation, while blunted or exaggerated CARs are linked to conditions such as chronic stress, PTSD, depression, chronic fatigue, and burnout. [4., 5., 7., 8., 9.] Assessing CAR through laboratory testing such as the Cortisol Awakening Response Profile by ZRT Laboratory can aid in identifying dysregulations in the hypothalamic-pituitary-adrenal (HPA) axis, which plays a central role in the body's stress response system. [1.]
The Cortisol Awakening Response (CAR) Profile by ZRT Laboratory may shed light on underlying health and disease factors in many groups of people, providing information that can direct the course of stress-related treatment:
Individuals with Stress-related Disorders: Research suggests that dysregulation of the CAR is associated with various stress-related disorders such as anxiety, depression, and post-traumatic stress disorder (PTSD). [3., 9.]
Individuals with Underlying Chronic Inflammation or Immune Dysfunction: the CAR may help clinicians understand the link between a patient’s mental or emotional stress and immune dysfunction (the mind-body connection). [3.]
People with Mood Disorders: Blunted or exaggerated CARs have been linked to mood disorders, including major depressive disorder and bipolar disorder, making CAR assessment valuable in diagnosing and managing these conditions. [1.]
Patients with Sleep Disturbances: Disturbances in the CAR have been observed in individuals with sleep disorders such as insomnia and obstructive sleep apnea, indicating the potential utility of CAR testing in evaluating sleep-related issues. [4.]
Individuals Experiencing Fatigue or Burnout: The CAR has been implicated in fatigue and burnout, with blunted CARs often seen in individuals experiencing chronic fatigue syndrome or burnout syndrome. [1., 4.]
People with Chronic Pain: Chronic pain conditions have been associated with alterations in the CAR, highlighting the relevance of CAR assessment in individuals with chronic pain conditions. [4.]
Individuals Undergoing Stress Management Interventions: CAR profiling can aid in monitoring the effectiveness of stress management interventions, allowing clinicians to adapt and emphasize treatment strategies based on an individual’s needs. [9.]
By assessing CAR, clinicians can gain insights into HPA axis function and stress response dynamics, facilitating personalized treatment approaches and improved patient outcomes.
Samples can be collected any day of the month.
Specific timing may be necessary if taking hormones.
Avoid anti-aging/anti-wrinkle facial creams for at least 3 days before collection.
Avoid eating, drinking anything but water, or brushing teeth for at least 2 hours before collection.
Freeze samples if not shipping within 24 hours of collection.
Collect samples any day of the month.
Avoid sublingual DHEA for 36 hours prior to collection.
For hormone users, avoid applying hormones with bare hands, take/apply night dosage 12 hours before morning collection, and change bedding/towels the night before.
Avoid 7-Keto DHEA and anti-aging facial creams for 3 days before collection.
People taking steroid medications should talk to their healthcare practitioner about proper timing.
Collect first saliva sample within 5 minutes of waking, without eating, drinking, or brushing teeth for 2 hours prior.
Wash hands and dry them with a clean towel, and rinse mouth before collection.
Fill tube at least half full within 5 minutes, without swallowing.
Repeat for subsequent collections according to schedule, followed by freezing if not shipping within 24 hours.
Patient Resource: How to Collect Your Saliva Sample
Collection 1: immediately upon waking
Collection 2: 30 minutes after waking
Collection 3: 60 minutes after waking
Now you can eat, drink, and brush your teeth.
Do not eat, drink anything but water, or brush your teeth for 2 hours prior to Collection 4.
Collection 4: Before lunch
Do not eat, drink anything but water, or brush your teeth for 2 hours prior to Collection 5.
Collection 5: Before dinner
Do not eat, drink anything but water, or brush your teeth for 2 hours prior to Collection 6.
Collection 6: Before bed
Freeze samples if not shipping within 24 hours.
Place sample tubes and completed requisition form into the test kit box, then into the provided return envelope.
Affix prepaid label and track return shipment.
Results available 3-5 business days after lab receives samples.
Provider will notify for a follow-up appointment to review results together.
[1.] Adam EK, Quinn ME, Tavernier R, McQuillan MT, Dahlke KA, Gilbert KE. Diurnal cortisol slopes and mental and physical health outcomes: A systematic review and meta-analysis. Psychoneuroendocrinology. 2017 Sep;83:25-41. doi: 10.1016/j.psyneuen.2017.05.018. Epub 2017 May 24. PMID: 28578301; PMCID: PMC5568897.
[2.] Ahn RS, Lee YJ, Choi JY, Kwon HB, Chun SI. Salivary cortisol and DHEA levels in the Korean population: age-related differences, diurnal rhythm, and correlations with serum levels. Yonsei Med J. 2007 Jun 30;48(3):379-88. doi: 10.3349/ymj.2007.48.3.379. PMID: 17594144; PMCID: PMC2628086.
[3.] Clow A, Thorn L, Evans P, Hucklebridge F. The awakening cortisol response: methodological issues and significance. Stress. 2004 Mar;7(1):29-37. doi: 10.1080/10253890410001667205. PMID: 15204030.
[4.] Fries E, Dettenborn L, Kirschbaum C. The cortisol awakening response (CAR): facts and future directions. Int J Psychophysiol. 2009 Apr;72(1):67-73. doi: 10.1016/j.ijpsycho.2008.03.014. Epub 2008 Sep 30. PMID: 18854200.
[5.] Lim WT, Torpy DJ. Chronic Fatigue Syndrome. [Updated 2023 Aug 30]. In: Feingold KR, Anawalt B, Blackman MR, et al., editors. Endotext [Internet]. South Dartmouth (MA): MDText.com, Inc.; 2000-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279099/
[6.] Stalder T, Kirschbaum C, Kudielka BM, Adam EK, Pruessner JC, Wüst S, Dockray S, Smyth N, Evans P, Hellhammer DH, Miller R, Wetherell MA, Lupien SJ, Clow A. Assessment of the cortisol awakening response: Expert consensus guidelines. Psychoneuroendocrinology. 2016 Jan;63:414-32. doi: 10.1016/j.psyneuen.2015.10.010. Epub 2015 Oct 20. PMID: 26563991.
[7.] Stanczykiewicz Bartłomiej Stańczykiewicz, Bogudzinska Bogna Bogudzińska, Kowalski KE, Misiak B. The association between depression and the cortisol awakening response is moderated by loneliness in men from a non-clinical sample. Psychoneuroendocrinology. 2024;160:106924-106924. doi:https://doi.org/10.1016/j.psyneuen.2023.106924
[8.] Wessa M, Rohleder, Kirschbaum C, Flor H. Altered cortisol awakening response in posttraumatic stress disorder. Psychoneuroendocrinology. 2006;31(2):209-215. doi:https://doi.org/10.1016/j.psyneuen.2005.06.010
[9.] Wüst S, Wolf J, Hellhammer DH, Federenko I, Schommer N, Kirschbaum C. The cortisol awakening response - normal values and confounds. Noise Health. 2000;2(7):79-88. PMID: 12689474.
The CAR Profile uses a six-point saliva collection to analyze cortisol patterns and assess adrenal hormone/HPA axis dysfunction.
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