Which hormone is most directly involved in the regulation of circadian rhythms?

Melatonin is the hormone most directly involved in the regulation of circadian rhythms. It is produced by the pineal gland in response to darkness and helps signal to the body that it is time to sleep. The secretion of melatonin typically increases in the evening as it gets dark, promoting sleepiness, and decreases in the morning with light exposure, aiding in wakefulness.

This process aligns the body’s internal clock with the external environment, acting as a key regulator of sleep-wake cycles. The presence of melatonin helps synchronize various physiological processes, including sleep patterns, metabolism, and even mood, with the natural light-dark cycle. Thus, its role is critical for maintaining a healthy circadian rhythm.

While cortisol and serotonin are also important in various bodily functions, they play different roles in relation to circadian rhythms. Cortisol follows a diurnal pattern, peaking in the early morning to help promote wakefulness and energy, rather than directly regulating circadian rhythms like melatonin does. Serotonin is involved in mood regulation and is a precursor to melatonin, but it is not primarily responsible for the timing of sleep and wakefulness. Oxytocin, primarily known for its role in social bonding and childbirth, does not have a direct function in