Reducing body temperature of rodents has been found to improve their surviv
al to ischaemia, hypoxia, chemical toxicants, and many other types of insul
ts. Larger species, including humans, may also benefit from a lower body te
mperature when recovering from CNS ischaemia and other traumatic insults. R
odents subjected to these insults undergo a regulated hypothermic response
(that is, decrease in set point temperature) characterised by preference fo
r cooler ambient temperatures, peripheral vasodilatation, and reduced metab
olic rate. However, forced hypothermia (that is, body temperature forced be
low set point) is the only method used in the study and treatment of human
pathological insults. The therapeutic efficacy of the hypothermic treatment
is likely to be influenced by the nature of the reduction in body temperat
ure (that is, forced versus regulated). Homeostatic mechanisms counter forc
ed reductions in body temperature resulting in physiological stress and dec
reased efficacy of the hypothermic treatment. On the other hand, regulated
hypothermia would seem to be the best means of achieving a therapeutic bene
fit because thermal homeostatic systems mediate a controlled reduction in c
ore temperature.