The Cortisol Awakening Response – also called CAR – reveals more detailed clues that help in assessing adrenal hormone/HPA Axis dysfunction. This testing is often useful for cases of PTSD, major depression, chronic fatigue syndrome and other severe stress conditions.
During a normal cortisol awakening response, adrenal hormone levels should increase 50% in the first 30 minutes after waking for the day and then begin to progressively drop through the afternoon and evening. To capture this response, three – rather than one – morning saliva collections are needed to properly chart the diurnal cortisol curve.
Cortisol Awakening Response Sample Collection
6-Tube Collection: Six cortisol collections in 24 hours is the most common method for assessing CAR. Start saliva collection within five minutes of waking for the day, followed by a second sample at 30 minutes, and a third sample at 60 minutes. The rest of the diurnal rhythm can be assessed at the normal time intervals – noon, evening and night (shown below).
4-Tube Collection: Alternately, CAR can be assessed with four cortisol collections in 24 hours. When using this method, collect a sample immediately upon waking, 30 minutes after waking, then at noon or evening, and night.
