Type D personality, the combination of negative affectivity and social inhibition, is associated with poor prognosis in patients with ischemic heart disease. The mechanisms are poorly understood. The aim of the present study was to examine whether Type D personality is associated with cardiovascular function in everyday life of people without documented cardiovascular disease. Eighty-six participants (53% women) aged 27 to 60years who reported work-related non-cardiac health complaints were equipped with ambulatory cardiovascular monitors for 24h measuring heart rate, respiratory sinus arrhythmia, pre-ejection period, and systolic and diastolic blood pressure. With and without controlling for age, sex, educational level, body mass index, physical activity, smoking and alcohol consumption, mood and social contact, Type D personality was not associated with any cardiovascular measure during the day or at night (all F (1, 79)<1.00, p>.10). When analyzed separately as continuous variables, only the social inhibition component of Type D personality showed a tendency for an association with nighttime systolic blood pressure (F (1, 78)=3.65, p=.06, η2=.04). In conclusion, Type D personality generally does not seem to be associated with unfavorable cardiovascular function in daily life of people without any documented cardiovascular disease.

Mechanisms relating Type D personality to poor health are largely unknown, with autonomic nervous system function being a candidate. This study examined the physiologic response to cold stress. Undergraduates (N = 101, 84% female) underwent a cold pressor test. An electrocardiogram, impedance cardiogram, and blood pressure were recorded. Type D personality was assessed by self-report questionnaire. Type D was associated with increased systolic and diastolic blood pressure reactivity. Exploratory analyses showed Type D men to respond with increased respiratory sinus arrhythmia (i.e., higher parasympathetic activity), and decreased pre-ejection period (i.e., larger sympathetic activity), while Type D women showed a reciprocal response pattern. In conclusion, Type D personality was associated with an exaggerated hemodynamic response to cold stress, which may contribute to an increased risk of hypertension in Type D individuals.

Background
There are large individual differences in dealing with everyday social stress. Therefore, we investigated the association of social inhibition (and its facets) with the emotional and physiological responses to the Trier Social Stress Test (TSST).
Methods
Undergraduate students (N = 312) completed the 15-item Social Inhibition Questionnaire (SIQ15) and participated in the TSST, while emotional and cardiovascular stress responses were recorded. We examined the effect of social inhibition across time with repeated-measures ANCOVAs.
Findings
During social stress (and recovery), social inhibition was associated with increased negative mood reactivity (especially the behavioral inhibition facet) and heightened sympathetic activation (especially the social withdrawal and interpersonal sensitivity). Physiological stress reactivity seems to be mostly α-adrenergic in women, and also β-adrenergic in men.
Conclusions
Emotional and physiological stress responses are associated with individual differences in social inhibition. This warrants more research on mechanisms that underlie the relations between social inhibition, stress and health.