Heart Rate Variability Associated with Experienced Zen Meditation
M Hoshiyama1,2, A Hoshiyama2
1. The University of Tokyo, Tokyo, Japan
2. Meisei University, Tokyo, Japan
ABSTRACT
To understand the control of hemodynamic events elicited by deep Zen meditation during Zazen, we studied heart rate in 5 experienced Zen meditators and 5 beginners. The study took place over 4 sets of Zen meditations in a quiet, Zen practice hall in Kamakura or Tokyo. Each set of Zazen lasted for 25 minutes which was preceded by specific respiratory exercise. The first sets were used for habituation, and the ECG data obtained from the following three sets were used for analysis. Power spectrum analysis showed a distinctive change in frequency components. Low and high-frequency components increased for experienced meditators. Most notably, detrended fluctuations analysis (DFA) of HRV were around 1/2 for experienced meditators and 0.78 for beginners. We attribute the decrease of DFA exponent in experienced meditators to the effective regulation of mind during meditation toward the edge of sleep, but not quite over it.
INTRODUCTION
Zen is a traditional meditation method which utilizes unification of body and mind. Though Zen has been sophisticated highly in Japan, it is spreading widely into the western world today, realizing deeper meditation with less effort.
While electroencephalogram (EEG) during Zen meditation has been studied in the past [1], there remains a lack of consensus whether heart rate during Zen practice elicits consistent heart rate variability (HRV) features. Research done in our laboratory aims at using the information contained in the fluctuation response of ECG heart rate to meditational state. To achieve this goal, it is necessary to understand better the mechanisms underlying the control of hemodynamic events through reciprocal autonomic activation elicited by meditational manipulation of body, respiration, and mind. Specifically, we are interested in quantifying the degree of difference between ECG interbeat interval fluctuation responses seen during experienced Zen meditators and beginners.
DISCUSSIONS AND CONCLUSIONS
During Zen practice, we seat ourselves in a lotus posture, practice Tanden respiration, i.e., lower abdominal breathing, and keep the mind free from a specific state of consciousness. Deep meditational state of Zen, namely Zanmai, can be accomplished after several years of Zen practice. This study was designed to elucidate the heart rate response to Zanmai by comparing beginners with experienced and practicing Zen meditators.
We could not find any difference in mean heart rate between beginners and experienced group. Significant differences exist, however, between the two groups in frequency components of the heart rate power spectrum. High-frequency component is around the frequency of respiration because it corresponds to respiratory sinus arrhythmia. The parasympathetic nervous system can transfer as high as 1Hz where respiratory sinus arrhythmia is transferred, but the sympathetic nervous system cannot transfer fluctuations higher than 0.15Hz. High-frequency component is modulated by the parasympathetic nervous system, but not by the sympathetic nervous system [6,7]. Mayer wave [8] in arterial blood pressure reflect itself to heart rate through arterial baroreflex which generates a low-frequency component of the heart rate variability [9,10]. Recently this low-frequency component has also been found in heart rate fluctuations under the artificial heart control suggesting the central origin of this autonomic nervous rhythm [11]. Since the low-frequency component is within the transferable frequency of the sympathetic nervous system, this component is modulated by both the sympathetic and parasympathetic nervous system. As mentioned above, the low-frequency component and high-frequency component increased for the experienced group. We attribute the increase in high-frequency component to the response of parasympathetic neural enhancement [12], and the increase in low-frequency component to the response of both parasympathetic and sympathetic arousal mechanism during Zanmai state of deep Zen meditation.
In the previous sleep studies, DFA exponent of HRV decreased from 0.8 to around 1/2 when they fall into a light sleep from awake [13,14]. We attribute the decrease of DFA exponent in experienced meditators to the effective regulation of mind during highly sophisticated Zen meditation toward the edge of sleep, but not quite over it. This result suggests the possibility of HRV as a handy and quantitative evaluator for Zen meditation.
Read the full study: HRV & ZEN MEDITATION