Introduction

When it comes to temperature control, the body runs a tight ship. The body carries out its business best at about 98.6° Fahrenheit (F), so the healthy body prevents its temperature from varying more than 1½° F from this desirable level. When the body's temperature gets much hotter or colder than 98.6° F, people generally feel terrible, functioning becomes impaired, and the results can be deadly.

Aging decreases the body's ability to control its temperature. In addition, older people are more likely than younger people to have diseases and to take drugs that decrease the body's ability to control its temperature. It should come as no surprise, then, that older people, compared with young and middle-aged adults, are much more susceptible to disorders in which body temperature falls dangerously low (hypothermia) or climbs dangerously high (hyperthermia).