Higher trait reappraisal predicts stronger HPA axis habituation to repeated stress.

Undergoing stress can be advantageous when it leads to adaptation and growth; however, failure of the hypothalamic-pituitary-adrenal (HPA) axis to habituate (i.e., nonhabituation) involves continuing to become highly activated in response to repeated exposure of the same stimulus and is considered maladaptive. Although 50-75% of individuals assessed in a laboratory exhibit adaptive habituation to repeated stress, variability in habituation suggests psychological processes used in response to stress may play a role, such as emotion regulation (ER). Nonetheless, no research to date has investigated whether ER strategies affect HPA axis habituation. We investigated whether tendency to use two ER strategies, reappraisal and suppression, influenced HPA axis habituation among 84 healthy young adults (60.7% female; Mage  = 24.8 years, SD = 6.0) exposed to a standardized experimental stress paradigm on two consecutive days. HPA axis stress responses were assessed using salivary cortisol concentrations. We also examined whether non-manipulated state ER strategies (i.e., those used by the participant during and following the stressor on the first day) modulated HPA axis habituation over and above trait-use in a subsample (N = 60). Trait, but not state, reappraisal was associated with stronger HPA axis habituation. Neither trait nor state suppression were significantly associated with HPA axis habituation. These findings expand our current understanding of how ER can affect stress-related health outcomes and suggest habitual reappraisal plays an important role in adaption of the HPA axis to stress.