The impact of experimentally instructed suppression on cardiovascular habituation during repeated stress.

Experimental research has shown instructed suppression is associated with heightened physiological responses during a single active stress exposure, with heightened responses to stress being a potential underlying mechanism linking suppression to cardiovascular disease (CVD). However, no research to date has examined instructed suppression with cardiovascular habituation to repeated stress. This study extends prior research by introducing a novel experimental paradigm, which incorporates a traditional suppression manipulation protocol within an active stress habituation framework. Between September 2022 and May 2023, participants (N = 244; mean (SD) age = 19.04 (1.9) years; 50.4 % women; 65.6 % White) completed a 10-min baseline, 5-min speech preparation, and 5-min speech delivery, which was repeated after a 10-min recovery. Participants were randomly assigned to either suppression or control instructions before the second speech prep. Heart rate (HR), systolic/diastolic blood pressures (SBP/DBP), and pre-ejection period (PEP) were measured throughout. State affect, perceived psychological stress, and state suppression were self-reported after each task. Habitual use of suppression was assessed using the Emotion Regulation Questionnaire. All participants exhibited significant cardiovascular habituation, irrespective of condition, suggesting instructed suppression did not hinder habituation. Instructed suppression was not associated with changes in perceived psychological stress or positive affect across tasks; however, instructed suppression was associated with greater habituation of negative affect. Neither state nor habitual suppression interacted with instructed suppression in influencing task responses. This is the first study to examine the relationship between experimentally instructed suppression and cardiovascular habituation, providing new perspective of the interplay between suppression and cardiovascular stress responding.