Hypothermia is widely considered to be a more serious threat for older
than for younger persons because of older persons' impaired ability t
o defend body temperature during cold exposure. Some epidemiological s
tudies indicate that the incidence of death from hypothermia increases
with age, but surveys of body temperature normally maintained by olde
r persons while in their own homes do not indicate a large incidence o
f hypothermia. More reliable comparisons of thermoregulatory responses
to cold stress in younger and older subjects have been performed unde
r controlled conditions in laboratory experiments. Generally, older me
n appear less able than younger men to defend their core temperature d
uring experimental cold exposures. Cold exposure may elicit a slightly
smaller rise in metabolic heat production, and the cutaneous vasocons
trictor response to cold may be less responsive in old than in young m
en. These aging effects may, however, be limited to men. In a recent s
tudy, older women appeared to defend core temperature during cold expo
sure as well as, or better than, younger women. Preventable changes in
body composition and physical fitness rather than aging per se may co
ntribute to impaired thermoregulatory responses to cold observed in ol
der workers.