Which small endocrine gland produces melatonin?

The pineal gland is the small endocrine gland responsible for the production of melatonin, a hormone that plays a crucial role in regulating sleep-wake cycles and circadian rhythms. This gland is located in the brain, specifically near the center, and is sensitive to light exposure. When it gets dark, the pineal gland secretes melatonin, signaling the body that it is time to prepare for sleep. Conversely, light exposure inhibits melatonin production, helping to regulate the sleep cycle by promoting wakefulness during the day.

The other glands mentioned do not produce melatonin; for example, the adrenal cortex is primarily involved in producing hormones such as cortisol, aldosterone, and sex hormones, which are key to regulating various bodily functions including metabolism and stress responses. The thyroid gland secretes hormones like thyroxine and triiodothyronine, which regulate metabolism, growth, and development. Meanwhile, the pancreas produces insulin and glucagon, which are essential for glucose metabolism and maintaining blood sugar levels. These functional differences highlight the specific role of the pineal gland in melatonin production.