What hormone is primarily responsible for the body's circadian rhythms?

Melatonin is the hormone primarily responsible for regulating the body's circadian rhythms. It is produced by the pineal gland in response to darkness, signaling to the body that it is time to prepare for sleep. This hormone plays a crucial role in the sleep-wake cycle, influencing sleep patterns and helping to synchronize various biological processes with the day-night cycle.

The secretion of melatonin typically begins in the evening, peaks in the middle of the night, and decreases towards morning as exposure to light increases. This pattern helps maintain the body's internal clock and promotes a regular sleep schedule, which is essential for overall health.

Understanding melatonin's function in circadian rhythms highlights the interplay between light exposure and hormonal regulation, which can impact sleep quality, mood, and even metabolic processes.