Sri Arunachala and Devi Parvati Temple Pictures

I recently came across a paper by some researchers in Thailand who recorded Heart Rate Variability in experienced Buddhist monks as they practiced concentrative meditation. They found that the monks naturally developed a high level of Heart Rate Coherence (HRC). This was of great personal interest to me because for some years now I’ve been using HRC in support of my meditation practice. In this blog post I explore the relationship between HRC and meditation and .

Here’s a link to the research:

The researchers simply recorded heart rate as the monks practised mindfulness of breathing meditation. The monks weren’t given any special instructions in terms of how to practice, and developing HRC was not their goal. And yet they spontaneously developed coherence as the monks entered Samadhi, a state of absorbed meditative concentration which is ‘a product of successful meditation’, as the researchers put it. Interestingly, the researchers distinguished between Samadhi and non-Samadhi meditation.

I explain , but to sum up it is a synchronisation between the breath and the heart rate, such that the heart speeds up on the inhalation and slows down again on the exhalation. The effect seems to be maximised at around 6 breaths per minute, which is in some sense a resonance point.

The monks in the study showed this coherence effect, which is seen as a clear peak in the spectral analysis graph of the heart rate data. Not all monks showed the peak at around 6 bpm, though most of them did. My interpretation of this is there is a synchronisation between the breath and the “heart wave”, but there is variability in the actual breathing rate – most breathing slowly and regularly at around 6 bpm, and some faster but still regularly.

What does this mean for meditators, especially for would-be Samadhi dwellers?

Two interesting possibilities suggest themselves to my mind (though they are by no means proven inferences).

The first is that, if as a meditator I can develop heart rate coherence, then Samadhi or one-pointed absorption is more likely. I think this idea is plausible if you believe in the mind-body connection – that subjective states of mind are reflected in physiological state and vice versa.

Secondly, feedback of the meditator’s degree of heart rate coherence, or rather changes in coherence, can help guide the meditator in the direction of greater concentration or Samadhi. For meditators the opposite of concentration is distraction, and the practice of mindfulness meditation is largely a matter of noticing distractions and returning to the object of focus. The trouble is, distractions are easy to spot if you’re not distracted, but very difficult once you’re into one. My thinking is, wouldn’t it be helpful if we could get some objective help in spotting distractions? This is where I see biofeedback helping.

An obvious counter-argument to these ideas is that developing HRC is not the goal of mindfulness practice. Deliberately breathing in a certain way is not mindfulness – rather, mindfulness is simply observing the breath as it is. If you’re trying to develop HRC, then it’s not mindfulness. Some might even argue that the attainment of Samadhi is itself not the goal of mindulness, in the sense that it doesn’t matter if you attain Samadhi or not, so long as you apply your mind to returning to the object of focus. This is what is meant by non-judgemental awareness.

I’ll leave the reader to decide. For me, I saw the research as a partial vindication of my own use of HRC biofeedback in meditation, and I was particularly happy to see that the difference between Samadhi and non-Samadhi meditation was reflected in the degree of heart rate coherence.