OBJECTIVE: Positive affect (PA) has been related to better health. However, the biological pathways underlying this link are not well understood. Different facets of PA (e.g., low activated vs. high activated) and both state and trait PA might have different effects on physiology. METHOD: This study aimed to relate low- and high-activated facets of momentary assessed (i.e., state) and aggregated (i.e., trait-like) PA to cardiac vagal tone (heart rate variability; HRV) in everyday life (N = 122, with 3 successive recording days). RESULTS: Aggregated activated PA was associated with higher ambulatory HRV, whereas activated momentary PA was accompanied by lower HRV. Moreover, momentary deactivated PA was accompanied by higher HRV, but aggregated deactivated PA was not. Findings were independent of negative affect and various other demographic and behavioral confounds. CONCLUSIONS: Together the findings suggest a more complex picture of the health-related effects of PA. Whereas state-related fluctuations in PA seem to exert both activating and deactivating effects on the heart, activated PA on an aggregated level seems to dampen cardiac arousal, thus suggesting beneficial effects for health.