Amplitude of the circadian rhythm of temperature in homeotherms

In most endothermic homeotherms, core body temperature follows a circadian rhythm. This review focuses on the amplitude of the circadian rhythm of body temperature (CRT) because the amplitude of the CRT has received increasing attention in the last few years. First, we discuss the methodology that can be used to measure the CRT, and the methodology used to calculate the amplitude of the CRT. Then, we illustrate the effect of changes in the external and internal environments on the amplitude of the CRT. Quite interestingly, as illustrated in this paper, while the molecular and hormonal basis of the CRT is well understood, the control of the amplitude is not. We conclude that challenges in the capacity of the animal to thermoregulate, or to manage energy, can impact on the amplitude of the CRT.