💀anatomy and physiology i review

Melatonin

Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025

Definition

Melatonin is a hormone produced by the pineal gland in the brain that regulates sleep-wake cycles. Its production increases in response to darkness, helping to promote sleep and adjust the body's internal clock.

"Melatonin" also found in: