title: Detailed time course of the cortisol awakening response in healthy participants.
abstract: The cortisol awakening response (CAR) can be assessed from saliva samples collected at home, which confers ecological validity but lacks researcher oversight. Participant non-adherence to requested saliva sampling regimes leads to inaccurate CAR estimates. Moderate sampling delays of just 8 (5-15) min between awakening and commencement of saliva sampling are reported to result in over-estimated CAR magnitude and earlier peaking. This has been attributed to an observed 'latent' period in which cortisol secretion does not increase for up to 10-min after awakening. Replication of this finding is essential as the findings have considerable implications for CAR research. Healthy participants (n=26) collected saliva samples at 5-min intervals for 60min on 2 consecutive typical weekdays. Full electronic monitoring of awakening and sampling enabled exclusion of non-adherent data (i.e., delays of greater than 5min between awakening and collection of the first sample). In the 0-15min post awakening segment of the CAR a quadratic effect was observed, with no difference between the awakening and 5 and 10min samples. Moderate sampling delays will shift assessment of the CAR just sufficiently along the time axis to not impact upon measurement of the first sample but to remove the immediate post-awakening latent period from CAR estimates-whilst retaining later estimates of elevated cortisol secretion. The implication from these results is that accurate CAR measures can only be determined from data with strict adherence to commencement of saliva sampling following awakening.
authors: Psychophysiology and Stress Research Group, Department of Psychology, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK.
authors: Nina
authors: N
authors: Smyth
authors: Psychophysiology and Stress Research Group, Department of Psychology, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK.
authors: Lisa
authors: L
authors: Thorn
authors: Psychophysiology and Stress Research Group, Department of Psychology, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK.
authors: Frank
authors: F
authors: Hucklebridge
authors: Psychophysiology and Stress Research Group, Department of Psychology, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK.
authors: Phil
authors: P
authors: Evans
authors: Psychophysiology and Stress Research Group, Department of Psychology, University of Westminster, 115 New Cavendish Street, London W1W 6UW, UK. Electronic address: clowa@wmin.ac.uk.
authors: Angela
authors: A
authors: Clow
mesh_terms: D000293:Adolescent; D000328:Adult; D002940:Circadian Rhythm / Q000502:physiology; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D007030:Hypothalamo-Hypophyseal System / Q000502:physiology; D008297:Male; D010913:Pituitary-Adrenal System / Q000502:physiology; D012463:Saliva / Q000737:chemistry; D013048:Specimen Handling; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*; D055815:Young Adult
chemical_list: D006854:Hydrocortisone
keywords: Adherence; CAR; Cortisol; Saliva; Timing; Wakening