Diurnal cortisol and rumination: Examining gender differences.

Emerging evidence from laboratory stressor studies suggests gender/sex differences in the relationship between the tendency to ruminate and prolonged activation of the hypothalamic-pituitary-adrenal (HPA) axis, as well as elevated levels of its end-product, cortisol. However, research on rumination and diurnal cortisol, particularly in relation to HPA activity and gender/sex differences, is limited. The primary aim of the present study was to extend laboratory findings to a naturalistic setting. Diurnal cortisol slope (DCS), a measure of typical decline in cortisol throughout the day, was examined. The study also examined whether rumination-cortisol associations differed by rumination type and gender/sex: stressor-focused rumination, which involves dwelling on past or current stressors, and brooding rumination, which focuses on evaluative reactions to sad emotions. The sample included 116 college-aged adults (63 women, 53 men) who provided six salivary cortisol samples throughout the day over five days. Analyses revealed that men and women differed in their associations between stressor-focused rumination and diurnal cortisol. Women with higher levels of stressor-focused rumination displayed flatter diurnal cortisol slopes, whereas the opposite pattern was observed in men. No such associations were observed for brooding rumination. Neither rumination measure was directly associated with diurnal cortisol. These findings suggest that women who engage in higher levels of stressor-focused rumination display altered diurnal cortisol in daily life, but not men.