What physiological change is commonly associated with circadian rhythms?

Circadian rhythms are natural, internal processes that follow a roughly 24-hour cycle and significantly influence various physiological functions in the body. One of the most notable physiological changes associated with these rhythms is the variation in hormone levels. Hormones such as cortisol, melatonin, and testosterone fluctuate throughout the day, with cortisol peaking in the morning to help wakefulness and melatonin rising in the evening to facilitate sleep.

This variation in hormone levels is tightly linked to the body's internal clock, which responds to environmental cues like light and darkness. It plays a crucial role in regulating sleep-wake cycles, metabolism, and other bodily functions. The changes in hormone levels help the body adapt to different times of day, optimizing performance, mood, and health.

In contrast, increased heart rate during nighttime, sudden drops in blood pressure, and consistent body weight are not directly governed by circadian rhythms. While heart rate may vary due to factors such as activity level and stress, it is not a primary indicator of circadian influence. Similarly, blood pressure fluctuations can occur for many reasons not specifically tied to the circadian cycle, and body weight can be influenced by long-term dietary patterns and metabolic health rather than daily biological rhythms. Thus, the variation in hormone levels