What it is
Melatonin is an indoleamine hormone synthesised from tryptophan by way of serotonin and released mainly by the pineal gland, strongly tied to the light–dark cycle. It is not a peptide.
In this article
What it is
Melatonin is a hormone synthesised from tryptophan by way of serotonin, released mainly by the pineal gland and strongly tied to the light–dark cycle. It is an indoleamine, not a peptide.
Research context
Grouped under sleep and mood research. Melatonin is the main chemical signal by which the body tracks the day–night cycle, so it is studied in circadian-rhythm contexts, shift-work and travel research, and light-exposure work. It also appears in antioxidant and aging literature.
Because it is sold over the counter in the United States, product quality varies more than for a regulated drug: independent analyses have repeatedly found supplement content differing substantially from label.
Status
- Regulatory status: Sold in the United States as a dietary supplement, not an FDA-approved drug. Prescription-only in several other countries, including much of the EU and the UK.
- Sport status: Not specifically listed on the WADA Prohibited List.
Reconstitution and handling
Reconstitution follows the standard math: concentration equals the milligrams in the vial divided by the millilitres of bacteriostatic water added. There is no single correct concentration — it depends on solubility and how large a draw is wanted. If a mix does not go fully clear, add more water. The reconstitution calculator shows concentration, draw size and portions per vial for any volume.
Refrigerate reconstituted vials at 2–8 °C, keep them out of light, wipe stoppers with alcohol before each puncture, and label with the mix date. Discard anything cloudy, discoloured, or with floaters.
Status in sport
Melatonin is not named on the WADA Prohibited List. Verify against the current year’s list, since classification can change.
Related reading
Reminder: research and educational reference only. Preppin Peppers sells hardware and materials, not peptides. Not medical, dosing, or health advice, not evaluated by the FDA, and not intended for human or animal use.
Frequently asked questions
Is melatonin a peptide?
No. It is an indoleamine hormone synthesised from tryptophan via serotonin. It is included in this reference library as a related research compound.
Is melatonin FDA-approved?
Not as a drug in the United States, where it is sold as a dietary supplement. Several other countries, including much of the EU and the UK, regulate it as prescription-only.
Why does melatonin content vary between products?
Because it is regulated as a dietary supplement in the US rather than as a drug, independent analyses have repeatedly found actual content differing substantially from what the label states.
What the research community gets wrong about Melatonin
- Supplement status is not a quality guarantee. Dietary-supplement regulation does not require the pre-market content verification a drug approval does, and independent testing has repeatedly found label mismatches.
- Vendor labels are not assays. Identity and purity come from a certificate of analysis on the batch in front of you, not from the name printed on a vial.
- A reconstituted vial does not stay good forever. Compounds in solution break down over time, and rough handling (shaking hard enough to foam) can damage them. Note the reconstitution date and store as your protocol calls for.
Sources
- PubChem Compound Summary: Melatonin
- NIH NCCIH — Melatonin: What You Need To Know
- Bacteriostatic Water for Injection, USP — FDA/DailyMed label (0.9% benzyl alcohol)
- Sigma-Aldrich (Merck) — Handling and Storage Guidelines for Peptides and Proteins
✔ Reviewed by Bryan Le, PharmD, RPh
Bryan is a licensed pharmacist (Doctor of Pharmacy, Registered Pharmacist). Reconstituting lyophilized preparations is core pharmacy practice, so he reviews The Lab’s content for technical accuracy and to keep it within a research-and-education scope, with no medical or dosing advice. View profile on LinkedIn.
