What is meant by the term 'circadian rhythm'?

The term 'circadian rhythm' refers to a biological process that follows a roughly 24-hour cycle, influencing a range of physical and mental changes in organisms. This cycle includes various physiological processes such as the sleep-wake cycle, hormone release, body temperature regulation, and behavioral patterns.

Circadian rhythms are regulated by internal biological clocks, primarily located in the suprachiasmatic nucleus of the hypothalamus, which receive input from the light-dark cycle in the environment. These rhythms help organisms adapt to the day-night cycle, facilitating appropriate physiological responses, such as increased alertness during daylight and restorative processes during sleep.

The other options touch on aspects related to circadian rhythms but do not encompass the full definition as completely as the chosen answer. Although hormonal release, sleep architecture, and body temperature can all be influenced by circadian rhythms, they represent specific outcomes rather than the comprehensive daily cycle of changes that the term encapsulates.