Written by the Fiveable Content Team • Last updated August 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated August 2025
Definition
Serotonin levels refer to the amount of serotonin, a neurotransmitter, present in the brain. This neurotransmitter plays a crucial role in regulating mood, sleep, appetite, and other physiological functions.