Investigating relations among stress, sleep and nail cortisol and DHEA

In the current study, we present data investigating the relationships among stress, sleep disturbance, self-control, and levels of cortisol (CORT) and dehydroepiandrosterone (DHEA) in fingernail clippings. Currently, hair CORT is the only routinely used noninvasive, validated, biomarker of chronic exposure to stress-related hormones. Nail clippings represent an important potential alternative sample matrix for assessing chronic hormone exposure, as it offers a different timeline of hormone incorporation than scalp hair, and may be obtainable from populations in which hair either is lacking or is unavailable for cultural reasons. Moreover, there is established precedent for using fingernail clippings to attain biomarker data. However, the value of nail hormone assessment for psychological research is currently unknown due to a paucity of information on the relations between nail hormone concentrations and environmental or psychological variables. In the present study, we collected data from a low income, minority population (N=47; 97% African American) to demonstrate feasibility and acceptability of nail collection and analysis of the adrenal steroids CORT and DHEA. Participants reported on perceived stress, sleep and self-control abilities. Correlational analyses suggest that exposure to stressful events, disturbances in sleep and waking were associated with higher levels of nail DHEA, while self-control was associated with higher levels of nail CORT. We discuss the potential importance of this methodology for investigating biological, behavioral, and subjective indices of stress and well-being.