Tasimelteon, developed by Vanda Pharmaceuticals Inc under license from Bristol-Myers Squibb Co, is a melatonin receptor agonist. Tasimelteon differs structurally from melatonin and drugs with known melatonin agonist activity, in particular by its distinct aromatic group and linker. Tasimelteon bears also no structural relationship to any other approved active substance. Tasimelteon is presumably acts through activation of MT1 and MT2 G-protein coupled receptors, which are involved primarily in inhibition of neuronal firing and phase shift of circadian rhythms. Tasimelteon is approved for the treatment of Non24-Hour Sleep-Wake Disorder.