Sleep supports cardiovascular, metabolic, neurologic, and psychological health. Beyond duration, circadian alignment is crucial because regular sleep, light exposure, feeding, and activity synchronize central and peripheral clocks. Modern chronodisruption from artificial light, irregular schedules, shift work, late eating, and insufficient sleep misaligns these rhythms and increases chronic disease risk. This review summarizes evidence linking sleep and circadian disruption to cardiovascular disease, metabolic dysfunction, and neurodegeneration. The American Heart Association's Life's Essential 8 recognizes sleep as a core cardiovascular health metric, reflecting evidence that sleep duration, timing, regularity, and quality add predictive value beyond traditional risk factors. We also review data from cohorts, proteomics, wearables, and artificial intelligence showing that objective sleep traits can predict cardiometabolic and neurologic outcomes. Both short and long sleep duration are associated with adverse metabolic outcomes, likely through partly distinct mechanisms. Finally, we discuss clinical implications, including light hygiene, meal timing, sleep disorder treatment, sleep metrics for early risk detection, and links between circadian disruption, gut microbiota metabolic reprogramming, clock-gene regulation, and diet-based strategies targeting gut-liver and metabolic pathways.
