Sleep and obesity are tightly interconnected, with bidirectional relationships that influence cardiometabolic health and the development and progression of sleep disorders. In this review, we synthesize current evidence linking insufficient sleep, insomnia, obstructive sleep apnea (OSA), and other sleep disorders with obesity, with a focus on pathophysiology, clinical implications, and emerging therapeutic strategies. Insufficient sleep is consistently associated with weight gain through hormonal, behavioral, and metabolic mechanisms, whereas the relationship between insomnia and obesity appears weaker and more heterogeneous. Obesity is a major driver of OSA via effects on upper airway anatomy, respiratory mechanics, and ventilatory control, though reciprocal effects of OSA on weight remain less clear. Recent advances in obesity pharmacotherapy, particularly incretin-based therapies such as dual GIP/GLP-1 receptor agonists, will likely reshape treatment paradigms. Clinical trial data demonstrate meaningful improvements in both weight and OSA severity, highlighting the potential for integrated management of comorbid obesity and OSA (COBOSA); however, traditional therapies-including continuous positive airway pressure (CPAP), exercise, and lifestyle modification-remain foundational components of care. We also review obesity hypoventilation syndrome and other sleep disorders associated with obesity, emphasizing shared and distinct mechanisms. Despite substantial progress, key knowledge gaps remain regarding optimal treatment integration, heterogeneity of treatment response, and long-term outcomes. Overall, effective management of obesity is increasingly central to sleep medicine, underscoring the need for multidisciplinary, patient-centered approaches and further research. Likewise, promoting adequate sleep should be considered an important component of weight management and overall health.
