title: Circadian variation in cortisol reactivity to an acute stressor.
abstract: To investigate the role of the circadian pacemaker in cortisol reactivity to a cold pressor challenge, 26 diurnally subjects participated in a constant-routine protocol and were divided into two groups. Group 1 started immediately after a monitored sleep period at 09:00 h, while group 2 started 12 h later. After 2 h of adaptation, a cold pressor test was presented every 3 h. The cortisol response was assessed by means of saliva samples that were taken before and after the test. The pretest samples were considered to be base-rate measures and base-rate values as subtracted from post-test values were considered as reactivity measures. Both measures showed distinct Time-of-Day variations (respectively: F(7,168) = 16.92, p < 0.001, epsilon = 0.383; and F(7,175) = 8.01, p < 0.001, epsilon = 0.523). These findings are interpreted as evidence for the existence of an endogenous circadian periodicity underlying the sensitivity of the hypothalamus-pituitary-adrenal (HPA)-axis to acute stress.
authors.affiliation: Department of Psychonomics, University of Amsterdam, Amsteradm, The Netherlands. eekelen@lumc.nl
authors.forename: Alexander P J
authors.initials: AP
authors.lastname: van Eekelen
authors.forename: Gerard A
authors.initials: GA
authors.lastname: Kerkhof
authors.forename: Jan G C
authors.initials: JG
authors.lastname: van Amsterdam
mesh_terms: D000293:Adolescent; D000328:Adult; D000339:Affect / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D003080:Cold Temperature; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000096:biosynthesis* / Q000502:physiology; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology; D008297:Male; D010913:Pituitary-Adrenal System / Q000503:physiopathology; D012463:Saliva / Q000378:metabolism; D013312:Stress, Physiological / Q000503:physiopathology* / Q000523:psychology
chemical_list: D006854:Hydrocortisone