A field (researcher's) guide to cortisol: tracking HPA axis functioning in everyday life

Abstract

Researchers have been incorporating ambulatory cortisol sampling into studies of everyday life for over a decade. Such work provides an important supplement to acute laboratory stress paradigms and provides a novel perspective on the interrelationships between stress, psychological resources, and health. However, the results of many field studies have been inconclusive and more studies have been undertaken than published. We describe some of the challenges facing naturalistic cortisol researchers, including lack of power, methodological and analytical problems, and patterns of confusing or conflictual results. We then summarize key findings of published naturalistic cortisol studies to date, grouped by type of cortisol outcome (morning awakening response, diurnal slope, area under the curve, and associations between momentary experiences and cortisol). We propose research questions relevant to everyday stress researchers and suggest next steps for researchers who are interested in incorporating naturalistic cortisol sampling into future studies.

Keywords:

• cortisol
• stress
• naturalistic research
• diurnal cortisol slope
• cortisol awakening response
• area under the curve
• research methodology

Acknowledgements

The author was supported by a National Science Foundation Graduate Research Fellowship and a ULCLA Chancellor's Dissertion Fellowship during the writing of this paper. She thanks Drs. Rena Repetti, Darglas Granger, Gregong Miller, Theodore Robles, and Chris Dunkel Schetter, as well as anonymous for valuable evidance and feedback.