Circadian Rhythm Disorders and Melatonin Applications

The circadian system orchestrates nearly every aspect of physiology and behaviour through an intrinsic near-24-hour clock. Disruptions of this clock manifest as circadian rhythm disorders, including delayed and advanced sleep phase syndromes, non-24-hour sleep–wake disorder and shift work disorder, leading to sleep fragmentation, daytime somnolence and cognitive impairment. Melatonin, the endogenous synchroniser secreted nocturnally by the pineal gland, has become a cornerstone for both diagnostic and therapeutic strategies. Exogenous melatonin and synthetic agonists act on MT1 and MT2 receptors to phase-shift oscillators within the suprachiasmatic nucleus and peripheral clocks, realigning internal time with external cues. Clinical applications span management of jet lag, delayed sleep phase in adolescents, free-running rhythms in blind individuals and emerging uses in psychiatric and metabolic conditions. Recent advances in formulation technology—such as prolonged-release preparations and selective receptor agonists—enable precise control over pharmacokinetics, enhancing efficacy for sleep initiation and circadian realignment. Growing evidence underscores the importance of optimising dose, timing and receptor selectivity to maximise therapeutic benefits while minimising side effects. As understanding of the molecular underpinnings expands, melatonin-based interventions are poised to play an increasingly personalised role in restoring circadian harmony across diverse patient populations.

Research from Nature Portfolio

Recent studies have elucidated the atomic structure of MT2 receptors bound to novel agonists, revealing conformational states that correlate with differential phase-shifting potency. These structural insights have informed the design of next-generation ligands with improved selectivity and stability. Parallel work employing genetically encoded bioluminescent reporters in peripheral tissues has mapped cell-type specific responses to melatonin, uncovering distinct roles in hepatic glucose regulation and immune function. In another development, large-scale genomic analyses have identified common variants in core clock genes that predispose individuals to shift work tolerance, providing a framework for genotype-guided interventions and personalised scheduling strategies.

Circadian Rhythm Disorders and Melatonin Applications publication trend

The graph below shows the total number of articles in circadian rhythm disorders and melatonin applications across all publications each year (not limited to Nature Index journals).

Technical terms

Circadian Rhythm: Endogenous near-24-hour cycle governing physiology and behaviour.

Entrainment: Synchronisation of internal circadian clocks to external time cues, primarily light.

Suprachiasmatic Nucleus (SCN): Hypothalamic master pacemaker coordinating peripheral clocks.

Melatonin: Pineal-secreted hormone that signals night and mediates phase shifts.

Melatonin Receptor Agonist: Exogenous compound activating MT1/MT2 receptors to modulate circadian timing.

Phase Shift: Adjustment of the timing of the circadian cycle forward or backward.

Non-24-Hour Sleep–Wake Disorder: Free-running circadian rhythm misaligned with the 24-hour day, common in blind individuals.

References

1. Melatonin: Countering Chaotic Time Cues. Frontiers in Endocrinology (2019).
2. Non-24-Hour Sleep–Wake Rhythm Disorder in the Totally Blind: Diagnosis and Management. Frontiers in Neurology (2017).
3. Tasimelteon: A selective and unique receptor binding profile. Neuropharmacology (2014).
4. New approaches in the management of insomnia: weighing the advantages of prolonged-release melatonin and synthetic melatoninergic agonists. Neuropsychiatric Disease and Treatment (2009).
5. Melatonergic agents influence the sleep-wake and circadian rhythms in healthy and psychiatric participants: a systematic review and meta-analysis of randomized controlled trials. Neuropsychopharmacology (2022).
6. Once-daily tasimelteon (VEC-162) for jet lag following transmeridian travel: A multicenter, randomized, double-blind, placebo-controlled trial. Frontiers in Neurology (2022).
7. Personalized medicine for pathological circadian dysfunctions. Frontiers in Pharmacology (2015).