Nocturnal difference in the ultra low frequency band of heart rate variability in patients stratified by Kampo medicine prescription

Background: The Yo/Yin concept is fundamental to making a Kampo (sho) diagnosis and may be deeply related to the autonomic nervous system. There is, however, little objective data to confirm the validity of these concepts. Methods and Results: After diagnosis using standardized Kampo techniques, 20 men and 67 women (mean age, 52.4 years) for whom the prescribed Kampo medication was effective were judged to be correctly classified as Yo-(n=49) or Yin-sho (n=38) and enrolled. Autonomic nervous function was assessed at first visit using HRV obtained from 24-h Holter ECG. Nocturnal ultra low frequency-1 (ULF-1, 0.0001-0.0003 Hz) and ULF-2 (0.0003-0.003 Hz) were significantly higher in the Yin-sho than in the Yo-sho group (P=0.030, P=0.016), suggesting a higher variation of autonomic nervous activity according to sleep stage. On multivariate analysis BMI (≥23.0 kg/m²) and ULF-1 (≥1,150 ms²) were identified as independent factors associated with a differential diagnosis of Yo-or Yin-sho (odds ratio [OR], 11.63, P=0.002; OR, 0.30, P=0.038, respectively). When the sleep period was divided into 3 phases, the ULF-1 of the Yin-sho group was significantly higher than that of the Yo-sho group in the late phase of sleep (P=0.023). Conclusions: On heart rate variability analysis there was a sleep stage-related difference in the autonomic nervous activity of patients treated with standard Yo-and Yin-sho Kampo medicines.