🧠ap psychology review

Melatonin

Written by the Fiveable Content Team • Last updated August 2025
Verified for the 2026 exam
Verified for the 2026 examWritten by the Fiveable Content Team • Last updated August 2025

Definition

Melatonin is a hormone produced by the pineal gland in our brain that regulates sleep-wake cycles. It plays a crucial role in setting our internal body clock (circadian rhythm) which affects sleep patterns.

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