Associations between inertia of negative emotions and diurnal cortisol in a sample of college students

Emotional inertia refers to the extent to which emotional states are predictable over time and are resistant to change. High emotional inertia, characterized by emotional states that carry over from one moment to the next, has been linked with both psychological maladjustment and impaired emotion regulation abilities. However, little research has examined the psychobiological correlates of emotional inertia. As such, in this study, we examined the association between inertia of negative emotions with cortisol, the end product of the hypothalamic pituitary adrenal (HPA) axis, one of the body's primary stress response systems. Participants were 76 college students (24% male, M_age = 18.53, SD = 0.37), who completed five corresponding daily diaries and salivary samples to ascertain cortisol per day for 3 consecutive days. Hierarchical linear models indicated that greater inertia of negative emotion across the three days was associated with smaller cortisol awakening responses (CAR) and lower AUCg, even when controlling for average negative emotion and momentary stress perception. There were no associations with the diurnal cortisol slope. These findings shed light on the neurobiological mechanisms involved in emotion dynamics.