We are warm-blooded (known as homothermal), and if the temperature of the air in which we live is lowered, our metabolic rate and bodily activity will increase to maintain our core temperature. This is hardly going to encourage life extension since by increasing our metabolic rate it does the very opposite to what we know to be necessary for life span to be lengthened. Life extension in humans would certainly not be achieved by lowering the environmental temperature, or Eskimos would live a very long time indeed, and they don't.

Actually the reverse is probably true, that whatever else is done to the atmosphere, a warm (not excessively hot either), ambient temperature would have the effect of reducing the work that the body has to do to maintain core temperature at its optimal levels, thus keeping calorie requirements low. We have seen that calorie restriction lowers metabolic activity, and that this is considered to be one of the key reasons why the dietetic approach seems to be able to extend life. The question, therefore, is whether there is any way in which human core temperature can be reduced, lowering metabolic activity, other than by calorie restriction? The answer is: possibly.

Our temperature is regulated by a control mechanism in the hypothalamic region of the brain, and if we are to influence our internal thermostat we have to find ways of affecting this region. Some drugs (including aspirin in a mild way) have been used to achieve lowered core temperature in animals, but this is hardly of interest in a natural life extension approach, although there is little doubt that some medications will eventually be marketed as life extension aids.

Techniques
Deep meditation and biofeedback techniques are methods which both allow humans to 1earn' to lower their core temperatures. By harnessing such methods to this task we could perhaps start to mimic the conditions known as torpidation (in winter) and estivation (in summer) which some animals achieve, producing a slowing down of metabolic activity (as in hibernation), at will.

It is reasonable to believe, based on the effects now monitored during years of investigation of deep relaxation/meditation techniques, that when these methods are practiced for modest periods daily, their effects cause a 'hangover' of slowed metabolic activity for some time afterwards. By spending two 20-minute periods daily practicing a form of deep relaxation, such as autogenic training, in which conscious images of a calmer, cooler, slower degree of metabolic activity are encouraged, just such benefits could emerge.

Living examples
One fascinating study of old people encourages the belief that this sort of effect is far from difficult to produce. As reported in Newsweek (5 March 1990, page 38), a group of 73 residents of old people's homes, average age 81, were asked either to practice relaxation, or transcendental meditation (TM), or nothing, and the differences in the three groups were observed for some years. Those doing TM had the best results in terms of lowered blood pressure, improved memory and survival. All of those doing TM were still alive after three years, whereas 12.5 per cent of the relaxation group and 37.5 per cent of the group doing neither TM nor relaxation had died.

Now, credit for this could be given to overall stress reduction, were it not for the fact that relaxation exercises reduce stress levels as well, but not core temperature. TM reduces stress and core temperature. Was this the effect which encouraged longevity in this elderly group? It was certainly doing them good and keeping them alive longer, which is another way of saying it was indeed encouraging longevity.

Biofeedback is a method much used in medicine today in which a small monitor is attached to the body to provide a visual or auditory signal, such as a high pitched sound or a readout on a small screen on which figures, such as blood pressure levels, are displayed. The patient has the task of using their mind to alter the sound or the numbers displayed, by in effect learning what their mind has to do in order to lower their blood pressure, or to alter the temperature of an arm or hand, for example.

Such techniques have been successfully used to alter circulation to, and drainage from, the head, in cases of congestion headache or migraine, and to alter circulation (and therefore temperature) in extremities, in order to warm or cool them, whichever was deemed more appropriate therapeutically.

Autogenic training (AT)
A method of achieving similar control of essential functions which would influence temperature directly is known as autogenic training. This originally German method has been further developed (largely in Canada) and is now widely and beneficially taught to people with a range of health problems. One of its key 'exercises' involves Iying or sitting comfortably, having first achieved a sense of relaxation, and then giving mental instructions to different parts of the body (say an arm or the forehead) to the effect that it is feeling either warmer or heavier or cooler, and then passively observing the area to evaluate the sensation. By repetition people rapidly learn to make an arm or foot warmer, or the forehead cooler (as evidenced by a skin thermometer) at will. There is no reason whatever to assume that they could not also learn to cool the whole body down, at will.

The techniques of TM and AT have to be learned from a teacher, and classes exist in all major centers. The methods can be described in a book but this is not the ideal way of learning them safely and thoroughly. The recommendation for those seeking natural life extension is that one or both of these methods should be learned and practiced, and then used as a part of everyday routine.