From Sun to Lamp: An Integrative Review on Circadian Disruption and Metabolic Risk in the Nutritional Transition of Traditional Populations

Artificial light has become a pervasive environmental exposure, yet its metabolic implications in populations historically synchronized with the solar cycle remain underexplored. Although the epidemiological transition in traditional communities is commonly attributed to dietary changes and physical inactivity, growing evidence indicates that light-at-night (LAN) may act as an independent metabolic disruptor. This integrative review examines how electrification and screen exposure affect circadian organization, meal timing, glucose metabolism, and cardiovascular risk in populations previously living without electric lighting. The objective was to critically synthesize empirical evidence on the association between artificial light exposure, circadian disruption, and metabolic outcomes, focusing on Indigenous, rural, and traditionally non-electrified communities. Searches in PubMed, Scopus, and Web of Science identified 278 records, of which 25 peer-reviewed original studies met inclusion criteria. Findings consistently show that electric lighting delays dim-light melatonin onset, reduces sleep duration, prolongs nocturnal eating windows, impairs glucose tolerance, and is associated with obesity, metabolic syndrome, and cardiovascular disease. Experimental and cohort studies converge in identifying LAN as a modifiable cardiometabolic risk factor. Electrification may impose urban temporal patterns on biologically solar-adapted bodies, underscoring the importance of integrating chrononutrition and sleep hygiene into public health strategies targeting traditional populations.