Which hormone is produced in the pineal gland and affects sleep cycles?

The hormone that is produced in the pineal gland and significantly affects sleep cycles is melatonin. Melatonin is synthesized from serotonin and is primarily responsible for regulating circadian rhythms, including the sleep-wake cycle. Its production is influenced by light exposure: levels typically rise in the evening as it gets dark, promoting the onset of sleep, and decrease in the presence of light, helping to regulate wakefulness.

Understanding the role of melatonin is crucial, as it helps establish a healthy sleep pattern and influences not just sleep but also the timing of various hormonal cycles in the body. This makes it an important hormone for overall well-being, especially regarding sleep quality and duration. The pineal gland acts as a biological clock, facilitating the body's adaptation to seasonal and daily changes in light, which is vital for maintaining homeostasis.