What is the Origin of Core Body Temperature Fluctuation?

This concept is foundational to chronobiology and thermoregulation, stemming from the observation of diurnal variations in human physiology. The fluctuation is a fundamental mechanism of homeostatic regulation, reflecting the body's metabolic preparation for periods of activity and rest.

What is the Mechanism of Core Body Temperature Fluctuation?

The suprachiasmatic nucleus (SCN) drives the circadian rhythm of core body temperature (CBT) by modulating the autonomic nervous system. The SCN signals the body to initiate peripheral vasodilation in the evening, increasing heat loss from the skin and causing the CBT to drop, which facilitates sleep onset. Conversely, vasoconstriction and increased metabolic heat production contribute to the rise in CBT throughout the active day, demonstrating a clear, inverse relationship between CBT and the propensity for sleep.

Core Body Temperature Fluctuation ∞ Area

Core Body Temperature Fluctuation

Meaning

Core Body Temperature Fluctuation describes the predictable, cyclical change in the internal thermal state of the human body over a 24-hour period, a central output of the master circadian clock. This rhythm is tightly regulated, exhibiting a high point in the late afternoon or early evening and a low point typically a few hours before waking. Monitoring this fluctuation provides a reliable physiological marker for assessing the phase and stability of the internal biological clock, crucial for clinical chronotherapy.