Melatonin is a powerful hormone (N‑acetyl-5‑methoxytryptamine) produced in the body's pineal gland, most prevalently during nighttime hours. Darkness triggers its release, while light suppresses it. Produced from tryptophan via serotonin, melatonin binds to receptors in the suprachiasmatic nuclei of the hypothalamus, and is thought to play a direct role in regulating sleep cycles.