Tibetan nuns are able to use meditation techniques to increase their core body temperature.
Scientists in Singapore say the discovery means core body temperature can be controlled by the brain - and could have major implications for people working in extreme environments.
The researchers have discovered that core body temperature can be increased by using certain meditation techniques.
They believe that meditation could, therefore, also be used to help people to function in very cold environments.
The team of researchers at the National University of Singapore showed for the first time that g-tummo meditation has been used by Tibetan nuns to increase their core body temperature.
Previous research has only shown that g-tummo meditators are able to increase the peripheral body temperature in their fingers and toes.
The researchers, who published their findings in the journal PLoS ONE, collected data during a unique ceremony in Tibet in which nuns raised their core body temperature and dried wet sheets which were wrapped around their bodies in -25 degree Celsius temperatures.
Using electroencephalography (EEG) recordings and temperature measures, the team observed increases in core body temperature up to 38.3 degree Celsius - normal body temperature is 37 degrees Celsius.
A second study was then conducted with Western participants who used a breathing technique of the g-tummo meditative practice and they were also able to increase their core body temperature, within limits.
The findings from this study showed that specific aspects of the meditation techniques can be used by non-meditators to regulate their body temperature through breathing and mental imagery.
This could allow them to adapt to, and function in, cold environments and could reduce performance problems associated with decreased body temperature.
The two aspects of g-tummo meditation that lead to temperature increases are 'vase breath' and concentrative visualisation.
'Vase breath' is a specific breathing technique which causes thermogenesis, which is a process of heat production.
The other technique, concentrative visualisation, involves focusing on a mental image of flames along the spinal cord in order to prevent heat losses.
Both techniques work in conjunction leading to elevated temperatures up to the level of moderate fever.
Associate Professor Maria Kozhevnikov from the Department of Psychology at the National University of Singapore, said: 'Practicing "vase breathing" alone is a safe technique to regulate core body temperature in a normal range.
A second study using Western participants showed that they were also able to increase their core body temperature using breathing and mental imagery.
'With further research, non-Tibetan meditators could use "vase breathing" to improve their health and regulate cognitive performance.'
Monasteries maintaining g-tummo traditions are very rare and are mostly located in the remote areas of eastern Tibet.
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