The diurnal patterns of the adrenal steroids cortisol and dehydroepiandrosterone (DHEA) in relation to awakening

Salivary VIP concentrations are elevated in humans after acute stress

“…DHEA levels also peak in the morning followed by a less pronounced decrease than cortisol (Hucklebridge et al;, Netherton et al, 2004 and finally research suggests amylase is lowest in the morning and higher in the afternoon and evening (Nater et al, 2007;Nater et al, 2009). Therefore, comparing our baseline results with the literature, we find good agreement for salivary cortisol and salivary DHEA from the different training exercises with the literature.…”

“…In addition to studying the pattern throughout the day, the investigators also study the awakening response for both steroids. Cortisol has a pronounced awakening response and is commonly known as the cortisol awakening response or CAR (Hucklebridge et al, 2005). The data clearly shows this response for cortisol for the first 45 minutes after awakening.…”

“…"Even the autonomic nervous system which is considered one of the main stress sensitive systems in humans shows a distinct circadian rhythm with sympathetic activity increasing significantly during the day and decreasing during the night, while the parasympathetic activity decreases during the day and increases during the night" Cortisol is known to have a distinct circadian rhythm with levels being highest in the early morning and decreasing throughout the day (Ahn et al, 2007;Krieger et al, 1971). Hucklebridge et al studied the circadian profile of both salivary cortisol and salivary DHEA in the same paper (Hucklebridge et al, 2005). In addition to studying the pattern throughout the day, the investigators also study the awakening response for both steroids.…”

“…However, Hucklebridge et al states that the difference is probably due to downstream regulation. Downstream cortisol is synthesized by 17 alpha hydroxylase activity and DHEA by 17,20-lyase activity of cytochrome p450c17, and therefore the dissociation between cortisol and DHEA in reference to the post awakening response is probably due to the differential regulation of these two enzyme activities (Hucklebridge et al, 2005). The authors raise an important point that because the dynamics between cortisol and DHEA are different in the early morning consideration must be given to collection time in relation to awakening in the assessment of cortisol/DHEA ratios (Hucklebridge et al, 2005).…”

“…Another limitation of the study relates to circadian variations as training exercise 1 took place at 1700 whereas training exercise 2 and 3 took place in the morning (0700 & 0600 respectively). Circadian rhythms have been described for cortisol, DHEA and amylase: cortisol levels are highest in the morning and decrease progressively for the rest of the day (Morgan et al, 2004;Brown et al, 2008;Hucklebridge et al, 2005);…”