Melatonin

"Melatonin peptide" is the term people search, but melatonin itself is not a peptide. It is a small indoleamine hormone made from the amino acid tryptophan, by way of serotonin and N-acetylserotonin, and it is released mainly by the pineal gland on a cycle tied to ambient light and darkness — not a chain of amino acids linked by peptide bonds the way an actual peptide is.

What it is

Melatonin (N-acetyl-5-methoxytryptamine) is an indoleamine hormone, not a peptide, despite the "melatonin peptide" label used across research catalogs. The label persists because catalogs often group short-chain and small-molecule research compounds under a single "peptide" category for consistency, not because melatonin meets the chemical definition. It is synthesized from tryptophan via serotonin, produced primarily by the pineal gland in a pattern tied to the light–dark cycle, and is chemically a small, lipid-soluble molecule with no amino acid chain, peptide bonds, or terminal modification sites.

This matters for anyone standardizing reconstitution notes across a research panel: peptide hormones such as tirzepatide or GHK-Cu are built from linked amino acid residues and can behave differently once dissolved, even when prepared with identical hardware. All material on this page is provided strictly for laboratory research reference.

Research context

Melatonin is not a peptide — it is a small, tryptophan-derived hormone produced by the pineal gland in response to darkness, though search and supplier listings often group it alongside peptide research materials, partly because it is reconstituted and stored the same way. In the literature it is studied mainly in circadian-rhythm research: light-exposure, shift-work, and travel-related sleep-cycle studies, since it is the body's primary day–night signaling molecule. A smaller body of work covers antioxidant and aging research.

Because melatonin is sold over the counter in the United States, product quality varies more than for a regulated drug: independent testing has repeatedly found supplement content differing substantially from the label — a variance worth checking against documentation before, not after, reconstituting a reference sample for research use.

Status

• United States: Melatonin is sold as a dietary supplement under DSHEA, not as an FDA-approved drug. It has not gone through FDA review for any indicated use.
• Elsewhere: The US supplement classification does not carry over globally. Several countries, including much of the EU and the UK, classify melatonin as prescription-only. Legal status depends on jurisdiction, not on any property of the compound itself.
• Sport status: Melatonin is not specifically named on the current WADA Prohibited List, which is revised annually. Athletes subject to testing should independently confirm current status with their governing body before assuming any substance is permitted — list entries and interpretations change between versions and vary by federation.

Reconstitution and handling

Concentration is milligrams of melatonin peptide in the vial divided by millilitres of bacteriostatic water added, which we stock in 30 ml vials for this step. There's no single correct concentration — it depends on solubility and the draw size wanted; if the mix doesn't go fully clear, add more water. Use the reconstitution calculator to see concentration, draw size, and portions per vial for any volume you choose.

Benzyl alcohol in bacteriostatic water is a preservative, not a stabilizer for the peptide itself: it lets a vial be punctured repeatedly instead of once. It keeps the solution sterile across draws — it doesn't extend shelf life, boost potency, or otherwise change how the peptide behaves once mixed.

Handling after mixing follows a short checklist:

• Refrigerate reconstituted vials at 2–8 °C, out of light.
• Wipe the stopper with alcohol before each puncture.
• Label every vial with the mix date.
• Discard if color or clarity shifts after mixing — cloudiness, or a tinted mix turning clear — rather than guessing at what changed.

Status in sport

Melatonin does not currently appear on the World Anti-Doping Agency (WADA) Prohibited List. That list is republished every year and can add or remove substances without individual notice, so a substance's status can change between one year's list and the next without warning.

• Confirm current status directly at wada-ama.org against the current year's list — not this page, and not any other third-party summary.
• Sport federations can apply internal rules that differ from WADA's list, so check with the relevant governing body if a federation code applies to you.
• This section is a reference summary only, not legal or compliance advice, and does not track any anti-doping code beyond WADA's own published list.

Frequently asked questions