09/04/2026
The pineal gland is a tiny endocrine gland deep within the brain that plays an important role in regulating the sleep wake cycle. It does not directly detect light. Instead, light information reaches the brain’s suprachiasmatic nucleus through the eyes, which helps regulate signals to the pineal gland.
When darkness increases, the pineal gland produces more melatonin, helping signal to the body that it is time for nighttime physiology and sleep.