Melatonin's role in the multiple internal clocks of mammals

Melatonin may stabilize and reinforce circadian rhythms by acting on the circadian clock.

• The suprachiasmatic nucleus (SCN) orchestrates circadian rhythms through a network of neural, hormonal, and behavioral signals.
• Melatonin serves as an endogenous synchronizer, providing circadian information to maintain the phase relationship of various oscillators.
• Exogenous melatonin can influence all levels of the circadian network, potentially impacting overall circadian function.
• In rats, REV-ERB alpha appears to be the initial molecular target for the chronobiotic effects of melatonin.

Simplified