Sleep is a complex biological process, essential for maintaining physiological balance and overall health. Circadian sleep disorders, and also other sleep conditions, such as insomnia and obstructive sleep apnea, can profoundly impact the metabolic, kidney, and cardiovascular systems, due to systemic inflammation, metabolic dysfunction, and autonomic imbalance. These are increasingly affected as the severity of sleep disorders increases. As such, a profound understanding of these interactions remains detrimental for effectively managing this complex multisystem disorder. Recognizing this interplay, in 2023, the American Heart Association introduced the concept of cardiovascular–kidney–metabolic (CKM) syndrome, reflecting the close interaction between metabolic, renal, and cardiovascular disorders. The syndrome’s emergence has marked a paradigm shift in understanding how seemingly distinct disease domains, metabolism, cardiovascular physiology, and renal function interact in a shared pathogenic framework. Therefore, a comprehensive understanding of how sleep and circadian disturbances can contribute to CKM pathogenesis is essential for improving prevention, diagnosis, and management.