Heart rate reactivity to laboratory tasks and in two daily life settings.

This study investigated relationships between laboratory task-related heart rate reactivity and heart rate responses in two daily life settings. The main purpose of the study was to demonstrate that the expression of heart rate reactivity during daily life depends on the nature of the daily life situation, or on subjective or behavioral responses in the daily life situation. Twenty-six healthy, male medical students completed one laboratory session consisting of pretask rest, reaction time, video game, and mental arithmetic conditions, and 2 day-long field study periods, during which subjects either worked as student physicians in a medical clinic or attended classroom lectures. After controlling for differences in daily life physical activity levels, (1) heart rate levels were significantly higher during clinic work periods, compared to classroom work periods and evenings of both days, (2) and heart rate responses to the tasks correlated significantly with minimum, mean, and maximum heart rate responses from the clinic work period, but not from the other field periods. Thus, individual differences in heart rate reactivity were found in one daily life situation, but not in another daily life situation. These results support the experimental hypothesis.