The role of week(end)-day and awakening time on cortisol and alpha-amylase awakening responses

Abstract

Awakening responses in salivary cortisol (CAR) and alpha-amylase (AAR) constitute proxies of morning activation patterns of the hypothalamic-pituitary-adrenal axis and autonomic nervous system, respectively. Previous studies suggest that the CAR is decreased at weekends and at late awakening. However, it is insufficiently studied (a) whether this also applies to the AAR and (b) whether week(end)-day and awakening time interact with each other. Using an ecological momentary assessment design, 48 healthy young adults (60% women) were investigated over a 7-d period (Study 1), and 27 chronic pain patients diagnosed with fibromyalgia syndrome were examined over a 14-d period (Study 2). For the assessment of the CAR and AAR, participants provided saliva samples each morning (upon awakening, 30 min after awakening). Preprogrammed electronic diary devices were used to track week(end)-day and exact time of saliva sampling (awakening time). In Study 1, CAR was unrelated to weekend, awakening time, or their interaction, whereas only early awakening time was positively associated with AAR. In Study 2, week-days as well as early awakening times on week-days predicted increased CAR. AARs were not predicted by week(end)-day, awakening times, or their interaction. These findings suggest that time-related factors may influence awakening responses, particularly the impact of week(end)-day on the CAR and the impact of awakening times on the AAR. Since week(end)-day and awakening times may negatively affect awakening responses, these potential confounding factors should be assessed and controlled for, particularly in studies assessing both CAR and AAR.