The pineal gland is a small, pea-shaped endocrine gland located in the brain. It is situated near the center, between the two hemispheres, and is responsible for producing the hormone melatonin, which regulates sleep-wake cycles. The gland is sensitive to light, helping to control circadian rhythms based on environmental light conditions. In addition to its role in sleep regulation, the pineal gland is often associated with various spiritual and mystical beliefs. Some cultures refer to it as the "third eye," linking it to intuition and higher consciousness. However, its primary function remains hormonal regulation and maintaining the body's internal clock.