What does the Salivary Cortisol — Morning (Waking, Cortisol Awakening Response) test measure?

Why is Salivary Cortisol — Morning (Waking, Cortisol Awakening Response) measured?

The morning waking cortisol and CAR are the primary indicators of HPA axis activation status and circadian integrity. A robust morning cortisol peak and a strong CAR indicate intact hypothalamic-pituitary-adrenal axis responsiveness and appropriate circadian entrainment. A blunted or absent CAR — below the expected 50–100% post-waking rise — is a validated biomarker of HPA axis hyporesponsiveness associated with burnout, chronic fatigue syndrome, post-traumatic stress disorder, and prolonged chronic stress; it also occurs in shift workers and individuals with circadian disruption. An exaggerated CAR is associated with high anticipatory stress, anxiety disorders, early-stage HPA hyperactivation, and early-morning awakenings. In functional and integrative medicine, the morning cortisol and CAR establish the anchor point of the diurnal curve from which the remainder of the daily pattern is interpreted.

Reference ranges

Standard reference

Waking: 3.7–9.5 ng/mL (10.2–26.2 nmol/L); 30 minutes post-waking (CAR peak): 7.0–18.0 ng/mL (19.3–49.6 nmol/L) # REVIEWER FLAG: Confirm Genova Diagnostics reference ranges for waking and 30-minute post-waking salivary cortisol — values are population-dataset-specific and not standardised across platforms. Confirm whether Genova captures the CAR as a discrete second time point or captures only a single morning waking value.

Functional medicine optimal

Waking: 5.0–8.0 ng/mL; CAR peak (30 min post-waking): 10.0–16.0 ng/mL with a CAR increment of ≥2.5 ng/mL above waking value (functional medicine optimal; reflects adequate but not excessive HPA axis morning activation). # REVIEWER FLAG: CAR increment thresholds and optimal ranges vary between HPA axis research literature and integrative clinical practice — confirm appropriate framing and whether Genova Diagnostics provides CAR-specific interpretive guidance.

Units

ng/mL, nmol/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.