Do state factors moderate the relationship between depressive symptoms and morning cortisol?

To fully capitalize on the utility of morning cortisol in biosocial studies of health and well-being researchers must carefully control for potential confounds. Recent reports have highlighted wake time, workday, and anticipatory negative emotions as regulators of intra-individual variation, with the potential to obscure cortisol-trait associations if not properly controlled. The purpose of this analysis is to examine the potential for trait-factors (i.e., depressive symptoms) to interact with state fluctuations in the prediction of morning cortisol. Saliva samples were collected from 56 working women at awakening and 30 min post awakening. Samples were collected on four consecutive days-two non-workdays followed by two workdays. Confirming prior research, morning cortisol levels were higher on work days and when individuals had early wake times. However, this relationship was strongest for women with fewer depressive symptoms. Similarly, only in women with fewer depressive symptoms was workday related to higher cortisol levels, and the anticipation of high negative affect related to steeper CARs and higher cortisol levels. Findings raise the possibility that certain populations may not be as physiologically sensitive to external regulatory cues, thus affecting intra-individual differences in HPA axis activity. Implications for future biobehavioral studies of depression and studies involving non-clinical samples are discussed.
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