Assessment of the cortisol awakening response: Expert consensus guidelines.
Stalder T1, Kirschbaum C2, Kudielka BM3, Adam EK4, Pruessner JC5, Wüst S3, Dockray S6, Smyth N7, Evans P7, Hellhammer DH8, Miller R2, Wetherell MA9, Lupien SJ10, Clow A7.
1. Department of Psychology, TU Dresden, Dresden, Germany. Electronic address: email@example.com.
2. Department of Psychology, TU Dresden, Dresden, Germany.
3. Department of Psychology, University of Regensburg, Regensburg, Germany.
4. School of Education and Social Policy, Northwestern University, Evanston, USA.
5. Department of Psychiatry, McGill University, Montreal, Canada.
6. School of Applied Psychology, University College Cork, Cork, Ireland.
7. Department of Psychology, University of Westminster, London, UK.
8. Department of Psychology, Trier University, Trier, Germany.
9. Department of Psychology, Northumbria University, Newcastle, UK.
10.Department of Psychiatry, University of Montreal, Montreal, Quebec, Canada.
The cortisol awakening response (CAR), the marked increase in cortisol secretion over the first 30-45min after morning awakening, has been related to a wide range of psychosocial, physical and mental health parameters, making it a key variable for psychoneuroendocrinological research. The CAR is typically assessed from self-collection of saliva samples within the domestic setting. While this confers ecological validity, it lacks direct researcher oversight which can be problematic as the validity of CAR measurement critically relies on participants closely following a timed sampling schedule, beginning with the moment of awakening. Researchers assessing the CAR thus need to take important steps to maximize and monitor saliva sampling accuracy as well as consider a range of other relevant methodological factors. To promote best practice of future research in this field, the International Society of Psychoneuroendocrinology initiated an expert panel charged with (i) summarizing relevant evidence and collective experience on methodological factors affecting CAR assessment and (ii) formulating clear consensus guidelines for future research. The present report summarizes the results of this undertaking. Consensus guidelines are presented on central aspects of CAR assessment, including objective control of sampling accuracy/adherence, participant instructions, covariate accounting, sampling protocols, quantification strategies as well as reporting and interpreting of CAR data. Meeting these methodological standards in future research will create more powerful research designs, thus yielding more reliable and reproducible results and helping to further advance understanding in this evolving field of research.