Monitoring of core body temperature in humans

Abstract

Humans have an endothermic metabolism which regulates core body temperature autonomously with a median of 36.7°C and in a circadian rhythm of 24.5 h with a range of ±0.5 °C. In the past, the possibilities of measuring core body temperature in humans to assess stress-dependent changes in the thermal regulation and to thereby monitor changes in circadian rhythm were too invasive or too inaccurate. A newly developed heat-flux sensor (Double Sensor) has become more feasible for use in field studies without disturbing the subject but with the high accuracy needed. This chapter reviews the options and pitfalls of core body temperature measurements, the principles of the heat-flux sensing, as well as its most recent applications in space as an extreme condition of life with environmental stressors that are significantly affecting thermoregulation.