Letter to the Editor Changes in heart rate variability during concentration meditation ✩ Sukanya Phongsuphap a, ⁎ , Yongyuth Pongsupap b , Pakorn Chandanamattha c , Chidchanok Lursinsap d a Department of Computer Science, Faculty of Science, Mahidol University, Rama 6 road, Ratchathewi, Bangkok 10400, Thailand b Health Care Reform Project, National Health Security Office, Nonthaburi 11120, Thailand c Department of Medicine, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand d Department of Mathematics, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand Received 12 May 2007; accepted 30 June 2007 Available online 30 August 2007 Abstract This study aims at investigating changes in heart rate variability (HRV) measured during meditation. The statistical and spectral measures of HRV from the RR intervals were analyzed. Results indicate that meditation may have different effects on health depending on frequency of the resonant peak that each meditator can achieve. The possible effects may concern resetting baroreflex sensitivity, increasing the parasympathetic tone, and improving efficiency of gas exchange in the lung. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Heart rate variability; Autonomic nervous system; Meditation; Pattern recognition 1. Introduction Originally, meditation is a spiritual practice in many religions. Nowadays, it can be practiced by anyone regard- less of their religions to facilitate a greater sense of calmness or awareness. There are many types of meditation techni- ques. The one adopted here is concentration meditation. The terms “meditation” and “Samadhi” used throughout this paper are defined as follows. Meditation is a practice of concentrated focus upon the breath in order to still the mind. Samadhi is the state of one-pointed concentration which is a product of successful meditation. In this study, we investigate changes in heart rate variability during concen- tration meditation to understand more its effects on health. Finally, we discuss and compare our results with those of the other meditation techniques [1–5] such as Qigong (Chinese style), Kundalini Yoga (Indian style), and Zazen (Japanese style). 2. Materials and methods 2.1. Subjects Thirty-five experimental subjects were recruited on a voluntary basis (mean age 33.40 years, mean weight 58.69 kg, mean height 165.63 cm). These thirty-five subjects are meditation practitioners who have experienced in achieving the Samadhi state and most of them are meditation masters. And seventy age-matched subjects who did not have any experience in meditation practice were recruited as a control group (mean age 33.56 years, mean weight 57.44 kg, mean height 162.56 cm). At the time of enrolment, all subjects were in good general health, free of any history of cardiac or vascular disease, did not follow any specific exercise routines, did not take any form of medication, and did not drink coffee or tea before meditation practices or data recording. They were non-smokers and none of them were habitual drinkers. The overall general health conditions for the meditation group and the non-meditating control group were comparable. Informed written consent was obtained from each subject after the experimental procedures had been explained. International Journal of Cardiology 130 (2008) 481 – 484 www.elsevier.com/locate/ijcard ✩ Grant Support:(1) The Thailand Research Fund (TRF)(2) The Commission on Higher Education, Ministry of Education, Thailand. ⁎ Corresponding author. Tel.: +66 2 354 4333; fax: +66 2 354 7333. E-mail address: ccsps@mahidol.ac.th (S. Phongsuphap). 0167-5273/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijcard.2007.06.103