Melatonin, biological rhythm disorders and phototherapy

Area of Science:

• Chronobiology
• Neuroendocrinology

Background:

• Biological rhythms are endogenous, generated by self-sustained oscillators.
• Circadian rhythms, driven by the suprachiasmatic nucleus (SCN) of the hypothalamus, are extensively studied.
• Melatonin, a hormone, is increasingly recognized for its role in biological rhythm regulation.

Purpose of the Study:

• To explore the role of melatonin in the generation and regulation of circadian rhythms.
• To investigate the involvement of melatonin in the pathogenesis of biological rhythm disorders.
• To highlight melatonin's broader physiological functions beyond rhythm regulation.

Main Methods:

• Review of existing literature on biological rhythms, melatonin, and associated disorders.
• Analysis of the significance of melatonin receptors (ML1, ML2) in the SCN.
• Correlation of altered melatonin levels with specific health conditions.

Main Results:

• High-affinity melatonin receptors (ML1, ML2) in the SCN indicate melatonin's involvement in circadian rhythm control.
• Biological rhythm disorders (DSPS, Jet lag, shift-work disorders, SAD) respond to phototherapy or melatonin.
• Altered melatonin rhythms are documented in conditions like depression and shift-work disorder.

Conclusions:

• Melatonin is a crucial regulator of circadian rhythms and is implicated in the pathophysiology of various rhythm disorders.
• Melatonin's functions extend to sleep control, body temperature regulation, reproduction, and antioxidant protection.
• Low melatonin levels in cancer and heart disease patients suggest its potential role in these conditions, warranting further investigation.