Hormone produced by the Pineal Gland
- meta-analysis: reduced sleep onset latency by approximately 7 minutes and increased total sleep duration by about 8 minutes
- Delayed Sleep-Wake Phase Disorder (DSWPD): helped individuals fall asleep 34 minutes earlier
- mixed results, limited benefit
- Long-term safety is unclear, with potential interactions with medications like blood thinners, seizure drugs, birth control, and those broken down by the liver
- study found 26% of 31 supplements contained serotonin, often mismatched with labels