Epitalon, also written as Epithalon, is a short synthetic tetrapeptide commonly described by the amino-acid sequence Ala-Glu-Asp-Gly. In longevity research circles, it is usually discussed because of its proposed relationship to telomere biology, telomerase activity, circadian regulation, and cellular aging models.

Those topics can sound more certain than the evidence allows. Telomeres are real. Telomerase is real. Cellular senescence is a major field of aging biology. But a peptide being studied in relation to those systems does not mean it has been proven to extend human life, reverse aging, treat disease, or produce predictable biological outcomes outside controlled research settings.