GR 196429, a melatonin receptor agonist, exhibits selectivity for the MT1 subtype. This compound not only promotes sleep and alters circadianrhythms but also stimulates melatonin release in mice.
PF-05236216 hydrochloride is a brain penetrant, potent and selective inhibitor of casein kinase 1 delta epsilon (CK1δ ε) that modulates circadianrhythms in mice.