Melatonin in Clinical Practice: Grey Zones Between Chronobiology, Insomnia and Consumer Supplementation

Melatonin occupies a paradoxical position in contemporary sleep medicine: despite its physiological role as a regulator of circadian timing, it is frequently used and perceived as a nonspecific “natural” hypnotic. Although melatonin demonstrates modest benefits for sleep initiation and clearer efficacy in circadian rhythm sleep–wake disorders, its clinical use is often undermined by diagnostic imprecision, inappropriate dosing, mistimed administration, inconsistent formulations, and inadequate patient counseling. Circadian disorders can be misclassified as primary insomnia, leading to symptomatic treatment approaches that fail to address the underlying phase misalignment. At the same time, supraphysiological doses and reflexive bedtime administration have become normalized despite evidence that melatonin acts primarily as a chronobiotic whose effects depend more on timing than dose. Regulatory inconsistencies and substantial variability in over-the-counter preparations further complicate safe and reproducible use. These factors contribute to avoidable treatment failure, inaccurate labeling of nonresponse, and persistent misconceptions regarding melatonin’s mechanism of action. Therefore, melatonin should be approached as a pharmacological intervention requiring the same diagnostic rigor, individualized dosing, and longitudinal assessment expected of other sleep therapeutics, particularly when integrated with behavioral and circadian interventions.