The frequent comorbidity of obesity and sleep disorders is well-established, with high-fat diet (HFD) serving as a critical modifiable factor whose mechanisms of action warrant further elucidation. This review systematically synthesizes the current evidence on how HFD-induced obesity affects sleep architecture and quality, aiming to integrate existing evidence and construct a multi-pathway synergistic mechanism network. Existing research indicates that HFD can disrupt sleep rhythms, reduce slow-wave activity, increase sleep fragmentation, and impair respiratory stability during sleep. The underlying mechanisms involve the interplay of multiple pathways, including dysregulation of orexin, leptin, ghrelin, and dopamine signaling, metabolic products, endoplasmic reticulum stress, and dysbiosis of the gut microbiota. By analyzing the heterogeneous evidence and clarifying the limitations and controversies in current research, we provide a theoretical foundation for future standardized mechanism validation and exploration of precise intervention targets.