In vertebrates, melatonin's functions extend to synchronizing sleep-wake cycles, encompassing sleep-wake timing and blood pressure regulation, as well as controlling seasonal rhythmicity (circannual cycle), which includes reproduction, fattening, molting, and hibernation.[4] Its effects are mediated through the activation of melatonin receptors and its role as an antioxidant.[5][6][7] In plants and bacteria, melatonin primarily serves as a defense mechanism against oxidative stress, indicating its evolutionary significance.[8] The mitochondria, key organelles within cells, are the main producers of antioxidant melatonin,[9] underscoring the molecule's "ancient origins" and its fundamental role in protecting the earliest cells from reactive oxygen species.[10][11]
^Boutin JA, Audinot V, Ferry G, Delagrange P (August 2005). "Molecular tools to study melatonin pathways and actions". Trends in Pharmacological Sciences. 26 (8): 412–9. doi:10.1016/j.tips.2005.06.006. PMID15992934.
^Hardeland R (July 2005). "Antioxidative protection by melatonin: multiplicity of mechanisms from radical detoxification to radical avoidance". Endocrine. 27 (2): 119–30. doi:10.1385/ENDO:27:2:119. PMID16217125. S2CID46984486.