What hormone is associated with promoting sleepiness?

Melatonin is the hormone that plays a crucial role in promoting sleepiness and regulating the sleep-wake cycle. It is produced by the pineal gland in response to darkness, signaling to the body that it is time to sleep. Melatonin levels typically rise in the evening as it gets dark, which helps to facilitate the onset of sleep, and decrease in the morning when it is light, helping to wake the body up. The regulation of melatonin is influenced by external light conditions, making it a key factor in the management of circadian rhythms and overall sleep quality. This hormonal function is vital for promoting rest and recovery, highlighting the importance of melatonin in health and wellness.