Melatonin deficiency and sleep fragmentation in frequent travelers: A modern circadian health crisis

Background: Frequent travel disrupts the circadian rhythm, often leading to disturbed melatonin production. This disruption contributes to sleep fragmentation, reduces sleep quality, and cumulative fatigue that many travelers experience as more than just temporary jet lag. Despite the growing spread of global travel, the long-term consequences of melatonin deficiency and chronic circadian misalignment remain underrecognized and insufficiently addressed. Aim: To review the available literature on how frequent travel leads to melatonin deficiency and sleep fragmentation and to highlight the need for better strategies to address this growing circadian health issue. Methods: A narrative review was conducted using 35 peer-reviewed articles identified through PubMed, Scopus, and Google Scholar. The studies were organized into six thematic categories: biological mechanisms of melatonin production, circadian rhythm disturbances and frequent long-distance travel (jet lag), sleep fragmentation – mechanisms and consequences, correlation between melatonin deficiency and sleep fragmentation, long-term health issues and current intervention strategies. Results: Melatonin deficiency and sleep fragmentation in frequent travelers, by disrupting the central circadian rhythm, are associated with a number of serious long-term health consequences, such as neurodegeneration and cognitive impairment, metabolic disorders and cardiovascular diseases, diabetes, obesity, mental health issues and increased risk of cancer. Further research is needed to develop better strategies for managing circadian rhythm disruption and reducing its long-term effects. Conclusions: The circadian rhythm dysfunction is closely connected to many future health problems. Addressing this growing issue requires greater awareness and more effective, evidence-based strategies to support circadian stability in those who travel regularly.