Studying ten meditators of Tibetan Buddhism, a recent international research project provides solid evidence for centuries-old reports that through the advanced meditation practice Tummo, often referred to as “Inner Heat” or “Psychic Heat”, the core body temperature can be raised significantly.
The Tummo (also “g-Tummo”) meditation practice is an advanced form of meditation that has been transmitted in the Vajrayana (or Diamond Way) traditions of Tibetan Buddhism for the last 900 years. The spectacular outer sign of this meditation is that adepts are able to significantly raise their body temperature to an extent that they can melt the snow around them or dry wet blankets thrown over their naked body – at least this is how the traditional stories go. Already in the early 1980ies researchers from the Harvard Medical School set out to investigate these claims. Visiting three tummo practitioners in the foothills of the Himalayas, the researchers captured increases of peripheral body temperature (at fingers and toes) during this meditation by as much as 8.3 degree Celsius, apparently confirming the claims. However, later on criticism was raised concerning these results, for instance that the temperature range (22 – 33deg C) was in the normal body temperature range. Furthermore, similar increases have been observed merely as a result of changes to respiration and/or muscle contraction and, in consequence, cannot unequivocally be interpreted as a result of the meditation practice per se.
Recently, an international team of researchers from the US, Singapore and Germany again ventured to the Himalayas to take a fresh and more detailed look at the issue. This time 10 meditators (7 female) from the Nyingma and Kagyu meditation traditions of Tibetan Buddhism took part in the study. By considering two important aspects of this meditation practice, they were able to advance the understanding of this curious effect. Generally, Tummo meditation consists of a mental component, where certain images are called to mind, and a bodily, somatic component, where specific breathing practices, body postures and physical body movements are combined. Furthermore, these breathing practices can either be forceful or gentle. To shed light on what is taking place during this type of meditation, the scientists aimed to distinguishing between these different components. The meditators were asked to go through a sequence of four meditation conditions: 1) forceful breathing exercises without the mental component, 2) gentle breathing exercises without the mental component, 3) forceful breathing exercises combined with the mental meditation component and 4) gentle breathing exercises combined with the mental meditation component. At the same time the scientists recorded the electrical brain activity using electroencephalography (EEG) and the peripheral body temperature (at the fifth finger) and core body temperature (in the armpit).
So, what are the main findings? First of all, the study confirmed that the meditators were able to increase their core body temperature (in the armpit) significantly. Also increases of the peripheral temperature at the fingers was observed, but the authors argue that these may merely result from changes in the position of the hand during the practice rather be caused by meditation or breathing techniques. Interestingly, the increase in core body temperature only happened during the forceful breathing periods (with and without meditation), not during gentle breathing. During the latter periods the meditators maintained the increased temperature, though. This observation seems to confirm the explanation provided by the meditators that forceful breathing meditation is used to increase the body temperature, whereas gentle breathing meditation is used to maintain it.
But as there was an increase in core body temperature resulting from the forceful breathing with and without meditation, what’s the purpose of the meditation, of calling certain images to mind? Well, the data also show that the core temperature reached the slightly feverish range (of up to 38.5 C) only when forceful breathing was combined with meditation, whereas during forceful breathing alone temperatures, although elevated, remained in the range of normal body temperature.
As mentioned in part 1, in addition to recording changes in body temperature the scientists also measured the electrical brain activity with EEG. The most prominent finding here was that one particular brain rhythm, the so-called alpha rhythm (oscillating in the range of 8.5–12.5 Hz), increased in power during forceful breathing. Interestingly, the greater the increase in alpha power achieved during tummo meditation was, the longer the core temperature rose, and the higher the achieved temperature was. New evidence from cognitive neuroscience indicates that this alpha rhythm might reflect that the brain is decreasing the distractibility of ‘‘external’’ sensory events to aid concentration on the internal mental activity. The results thus seem to indicate that the quality of the meditation during forceful breathing, as reflected by increased alpha power, seems to determine for how long the meditators are capable of continuing to raise their body temperature beyond the normal range without reaching an equilibrium phase.
In sum, the study confirms the knowledge from Tibetan Buddhist traditions that the body temperature can be raised through tummo meditation. The authors discuss what the benefits of this ability might be and consider positive effects like adapting to and functioning in cold environments, improving resistance to infections, boosting cognitive performance by speeding response time, etc. However, they also point to another aspect that will probably be of higher importance to the yogis engaging in this advanced form of meditation. Although the rise in body temperature is neither solely a by-product of the meditation nor its final goal, but instead may be a means to facilitate the achievement of ‘‘deep meditative states’’ by enhancing their attention and focus.
There may also be a caveat: As such types of advanced meditations are practiced within a well-defined context, guided by experienced meditation teachers, building on years of personal practice that prepare the meditator and embedded within a complete meditation system, it might be difficult to predict what the results might be, should one try to engage with these exercises without proper preparation and supervision. After all, within Vajrayana traditions such meditations are only passed on to ‘well-prepared’ students, usually within the context of a relatively long retreat. The aim of these meditations would be to provide entry into advanced insight into mind as expounded in the traditions of the Great Seal (Sanskrit: Mahamudra, Tibetan: Chag Chen) and the Great Perfection (Sanskrit: Maha Ati, Tibetan: Dzog Chen).
References
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Kozhevnikov, M., Elliott, J., Shephard, J., & Gramann, K. (2013). Neurocognitive and somatic components of temperature increases during g-Tummo Meditation: Legend and reality. PLoS ONE 8(3), e58244. https://doi.org/10.1371/journal.pone.0058244
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Benson, H., Lehmann, J. W., Malhotra, M. S., Goodman, R. F., Hopkins, J., et al. (1982) Body temperature changes during the practice of g-tummo yoga. Nature 295, 234–236. https://doi.org/10.1038/295234a0.
