Blog — Second Measure

The Cortisol Awakening Response (CAR) and Adrenal Function

Posted by Ben White on

Cortisol should increase around %50 in the first 30 minutes on awakening then start to progressively drop the remainder of the day. Three, rather than one, early morning collections are what is needed to accurately assess the CAR; one immediately on waking, one 30 minutes later, and another at 1 hour. Diurnal Rhythm Assessment Thirty minutes after awakening from a good night's sleep, cortisol levels are at the highest they'll be all day. Following the morning peak, cortisol levels then fall to less than half that peak level by noon. They continue to drop to very low levels at night where...

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