In Magic and Mystery in Tibet Alexandra David-Neel talks about the incredible ability of certain Tibetan monks. They are reputedly able to raise their body temperature at will. She writes of monks draped in wet sheets at -35 degrees C and great gouts of steam rising from the wet cloths as their superheated bare torsos turned the icy garment into something like a steaming pudding cloth. Other travellers have also made passing mention of this technique but it wasn’t until the 1980s that Western science was able to catch up with Eastern expertise.
Greater knowledge of Tibet and her monks- whether they live on the Indian side or the Tibetan side of the border, indicated that the monks involved were practitioners of gtum-mo- (pronouced ‘dumo’) a form of breathing found in the teachings of the Tibetan Vajrayana. This was derived originally from the Indian Buddhist Vajrayana tradition.
Gtum-mo is a combination of breathing exercises and meditative concentration. The basic form involves performing ‘the vase’- this is a breathing technique where air is brought deep into the lower abdominal region and held there, making a pot belly or ‘vase’ of the stomach. There is a forceful version of this where the air is sucked in, held and then expelled with great vigour. There is a also a gentler version where the transitions are far less marked and the intake and exhalation of breath, though deep, is gentle.
Accompanying the breathing are two varieties of meditation. For the forceful breathing (which is used to ramp up body temperature quickly from ‘cold’ so to speak) the meditation is to picture internally an inner flame, something like a Bunsen burner flame, roaring hot, that starts at the navel and shoots up to the crown of the head. You have to imagine that flame in all its heat, roaring noise and light burning up through the core of the body.
For the more gentle variant of body temperature manipulation the mental image is of a surging sensation of bliss and rising warmth throughout the body.
In January 1982 Professor Herbert Benson reported in the august pages on Nature on his studies into what he termed gTum-mo yoga. Conducted in the Dharamsala monastery of the Dalai Lama’s government in exile, three monks were able to raise the temperature of their fingers and toes by a creditable 8.3 degrees C. This is rather impressive- certainly it would make the difference between frost bite and frost nip or merely coldness. If climbers and others who venture into highly refrigerated environs could learn these techniques many digits might be saved.
In 2002 Harvard Gazette reported 2 monks- of Western origin and living in Normandy- who were able to raise their body temperature using gtum-mo techiniques.
But it wasn’t until 2013 that a more comprehensive set of tests and a general survey of previous attempts was made. In the previous thirty years it had been found that raising peripheral temperatures- of hands and feet- could be made quite easily through various easily taught meditations, and, in fact, by training people to use simple biofeedback techniques. Typically a digital thermometer would be connected to sensors on the subject’s hands and feet. By sensing a greater awareness of the temperature of the hand or foot, whilst avoiding trying to force it up, the temperature could be made to rise as long raising temperatures was what was on the agenda.
But complications entered the field when it was found that raising core body temperature did not accompany raising peripheral temperatures. One theory suggested that various forms of muscular contraction served to raise hand temperature.
In the 2013 tests Dr Maria Kozhevnikov and her colleagues showed that unlike biofeedback results, gtum-mo genuinely raised core body temperatures- so much so that the wet sheet dried by body heat alone was shown to be fact not fiction.
Kohevnikov located one of the very few nunneries where a body temperature raising ceremony exists. This was at the 4200 metre high Gebchak convent close to Nangchen in Qinghai province. The ceremony was held annually and the nuns participating would wear only a short skirt, shoes or sandals with a wet cotton sheet draping the rest of their body. It would be performed in winter when air temperatures would be dry but -25 to -30 degrees C. Anyone who has dipped their hand in water at these temperatures will know the extreme discomfort involved, and how hard it is to regain skin warmth after drastic colling like this has happened. Ranulph Fiennes dipped his hand in icy sea water to release a sunken sledge and did not dry and warm the hand immediately. He later remarked that these two minutes of carelessness cost him the finger tips of that hand. I’ve swept a frosty tent surface with a bare hand at -15 degrees C and found the hand still cold even ten minutes later after wearing a mitten. Such anecdotal evidence makes even the existences of the sheet ceremony all the more impressive.
The nuns were aged between 25 and 52 years old and some performed the forceful variety of gtum-mo and some the more gentle kind. It was reported that the forceful kind could not be sustained for very long, so it was used to warm the body up, after which the gentle type would be used when walking and wearing the wet sheet.
Nuns raised their peripheral temperatures easily by 1.2 to 6.8 degrees C. More importantly the forceful type of gtum-mo raised core body temperature by over a degree. One woman was able to get it higher and only stopped because she felt uncomfortable. Another stopped because she was developing fever symptoms.
If peripheral temperature raising results in a lowering of core body temperature then using techniques to merely warm the hands might actually hasten hypothermia. However, if, as the gtum-mo tests show, you can raise core body temperature and peripheral temperature you have the means to withstand great cold- as the nuns show during their freezing sheet ceremony.
As a control a group of westerners who had some experience of yoga or meditation or kung fu, were taught the gtum-mo technique. Very quickly they were able to show similar effects of raised body temperature as the much more experienced Tibetan nuns. Something that appears mysterious and oriental turns out to be rather ordinary after all. I for one will certainly be using it when I next find myself shaking with cold in some Himalayan fastness.
 Herbert Benson “Body Temperature changes during the practice of gTum-mo yoga” Nature 295 21 Jan 1982
 Maria Kozhevnikov March 29 2013 PLoS ONE “Neurocognitive and somatic components of Temperature Increase during g-Tummo meditation”.