Anticipated stress predicts the cortisol awakening response: An intensive longitudinal pilot study.

The cortisol awakening response (CAR) has been hypothesized to prepare the body for anticipated demands of the upcoming day. This pilot study investigates the influence of anticipated stress on the upcoming day on the CAR, using an intensive longitudinal design with ecological momentary assessments. Over a 30-day period, three healthy participants collected saliva samples each morning at three time points after awakening to measure cortisol levels and completed a questionnaire each evening on the anticipated stress for the following day. Additionally, they wore a smart headband to objectively determine the time point of awakening. There was high variability in the CAR magnitude within participants over time. A multi-level model was estimated to investigate the influence of anticipated stress on the CAR. Results indicated that anticipated stress is predictive of the CAR on the following morning, with higher anticipated stress being associated with increased cortisol levels at the post-awakening time points. These findings underscore the role of stress anticipation in modulating the CAR and highlight the importance of considering within-person variation and temporally lagged effects in biopsychological research.