What aspect of sleep does melatonin help to adjust?

Melatonin is a hormone that plays a crucial role in regulating circadian rhythms, which are the natural cycles of physiological processes that occur roughly every 24 hours. 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 helps to synchronize the body’s internal clock with the external environment by responding to changes in light exposure.

Circadian rhythms control not only sleep-wake cycles but also various bodily functions, including temperature regulation, hormone release, and metabolism. By adjusting these rhythms, melatonin can significantly influence when a person feels alert or sleepy, therefore promoting a structured sleep schedule that aligns better with day-night cycles.

Other options, such as stage duration, exposure to light, and overall sleep quality, while related to sleep, do not directly capture the primary function of melatonin, which is to coordinate the timing of sleep in relation to the circadian rhythm. Stage duration refers more to the length of different sleep stages during the sleep cycle rather than the regulation of sleep timing. Exposure to light can influence melatonin production but isn't the primary function of melatonin itself. Overall sleep quality can be affected by various factors beyond melatonin alone, making it a broader concept.