OBJECTIVES: This report investigates whether there is any association between sense of coherence (SOC), as a coping measure in confronting stressful conditions, and heart rate variability (HRV), as a measure of the cardiac autonomic nervous system during the daily life pattern. METHODS: Sixteen healthy university students (14 males and 2 females) filled in the validated Japanese version of the SOC-13 questionnaire before being informed about the study protocol. For each participant, we calculated 5-minute HRV indices using logarithmically transformed data on frequency domains for HRV derived by 24-hour Holter monitoring. Frequency domains for HRV recordings were investigated for the 24-hour time periods. RESULTS: The correlation coefficient between the SOC scores and the high frequency power of HRV (0.15-0.40) was positively significant during the resting sitting position (r>/=0.60, P<0.05). After grouping SOC scores by the median, the high frequency domain of HRV was higher in high SOC subjects for most of the 24-hour time period. CONCLUSION: A higher SOC could modulate the parasympathetic tone of cardiac autonomic activity, especially during the resting sitting position.