Background: Positive affect (PA) has been suggested to benefit health via psychobiological pathways. Studies found higher cardiac vagal tone in individuals who exhibit a positive emotional style.
Purpose: This study aimed to examine the relationship between momentary-assessed PA and nocturnal heart rate (HR) and heart rate variability (HRV) in everyday life.
Methods: Participants were 60 healthy adults who provided multiple ratings of activated (e.g., dynamic, activated) and deactivated PA (e.g., relaxed, even-tempered) and negative affect (NA) throughout one day. HR and HRV were recorded the subsequent night.
Results: Aggregated deactivated PA throughout the day was associated with higher nocturnal HRV and lower HR. Activated PA and NA were unrelated with both cardiac variables. Findings were independent of other demographic and behavioral confounds.
Conclusions: Feeling relaxed, calm, content, and even-tempered throughout the day might have beneficial effects on the heart during sleep, although the causality of this effect remains speculative because of the correlational design of this study.