This chapter from the book MindScience : An East-West Dialogue is a record of a presentation given by Harvard doctor Herbert Benson during a conference between the Dalai Lama and psychologists, psychiatrists, neuroscientists, and psychobiologists at Harvard Medical School on March 24, 1991. The purpose of the conference, in part, was to share with the Dalai Lama and the medical community some of the scientific studies performed by Herbert Benson with Tibetan monks practicing "Tummo" (gtum mo) or the meditative generation of inner heat.

Herbert Benson gives an account of his experiences and the scientific findings from studying the physiological effects of meditation, starting in 1967 with practitioners of transcendental meditation and then eventually working with Tibetan monks with an expertise in the practice of "inner heat" (gtum mo). He specifically discusses how these types of meditative practices can significantly increase or decrease metabolism. Dr. Benson describes the nature of the studies performed with Tibetan monks, including the specific physiological changes he measured such as skin temperature and oxygen consumption. He also gives a general overview of the medical understanding of temperature regulation, looking specifically at the how warm-blooded animals regulate temperature through (1) heat production and (2) heat conservation.

Heat production can result through muscle activity and through chemical changes, such as chemical changes effected by the hormones epinephrine and thyroxin. Heat conservation is achieved in a variety of ways such as reducing the amount of skin exposure to the cold, piloerection (raising of hair, humans replace this by wearing clothing), and reducing blood flow to the extremities (where it will cool more rapidly). When put in a cold environment, the body naturally reduces blood flow to the extremities. However, practitioners of inner heat do the opposite: they increase the surface temperature of the skin. They also increase their metabolism.

Dr. Benson also discusses how his studies on meditators, in general, relate to what he calls the "relaxation response." This system is the opposite of the "stress response" which is involved with physiological reactions of "fight-or-flight." Research on the relaxation response has opened the door for its use in clinical settings for treatment of hypertension, cardiac arrhythmias, chronic pain, insomnia, the side of effects of cancer and AIDS therapies, anxiety disorders, depression, menstrual tension and infertility, and is also being applied as a preparation for surgery.

Finally, Dr. Benson answers questions from the audience on how his work relates to hypnosis, the treatment of cancer, the effect of meditation on blood carbon dioxide levels and blood pH, as well as other issues involved in the study of meditation. (Zach Rowinski 2005-01-04)