Abstract | Indices of post awakening cortisol secretion (PACS) provide an index of HPA axis function and are related to a wide range of psychosocial and health variables. Indices include the rise (cortisol awakening response: CAR) and overall concentrations (e.g. area under the cortisol curve with reference to ground: AUCg) in the first 30–45 min following morning awakening. However the relationship between the PACS and post awakening melatonin secretion (PAMS) is unknown. Here we report salivary cortisol and melatonin concentrations from healthy females (N = 41) and males (N = 10), age 21.6 ± 5.0 years, on 2 days at 15-min intervals for 45-min post-awakening. Perceived stress in the last month and well-being were also assessed. Awakening-time and sample timing accuracy were electronically-monitored to assess non-adherence. Data revealed the typical post-awakening CAR (p < .001), peaking at 45-min post awakening. In contrast there was no change in melatonin concentration across this time (p = .844) and neither the CAR nor AUCg were related to average melatonin (p = 0.709 and 0.906, respectively). Controlling for non-adherence using data from adherent sampling days only (i.e. first sample collected within 5-min of awakening as in Smyth et al., 2013; N = 61 days) cortisol AUCg was negatively associated with well-being (p = .035), independent of stress, awakening-time, gender and smoking. Melatonin secretion was not associated with well-being or perceived stress. We conclude that PACS and PAMS are unrelated and that PAMS does not contribute to the reported association between PACS (AUCg) and well-being in this study. |
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