What endocrine gland hormone production is influenced by presence or absence of light?

The pineal gland produces the hormone melatonin, which is influenced by the presence or absence of light. During periods of darkness, melatonin production increases, promoting sleep and regulating circadian rhythms. Conversely, exposure to light suppresses melatonin secretion, helping to keep the body alert and awake during the day. This regulation helps synchronize the body's internal clock with the external environment.