Melatonin (Circadin; 5-Methoxy-N-acetyltryptamine; NSC-56423; NSC 113928; Regulin), an endogenous indoleamine neurohormone associated with control of the sleep–wake cycle, is a MT receptor agonist used as a dietary supplement for controlling of circadian rhythm.

Ramelteon (formerly TAK-375; TAK375; trade name: Rozerem), an approved medication used to treat sleeplessness / insomnia, is a melatonin receptor (MT) agonist for human MT1 and MT2 receptors and chick forebrain melatonin receptors with Ki of 14 pM, 112 pM and 23.1 pM, respectively.