INSUFFICIENT AND DISRUPTED SLEEP IN METABOLIC DISEASE: A CRITICAL REVIEW OF INSULIN RESISTANCE

Sleep duration, continuity, and circadian timing may influence insulin action, but insulin resistance, dysglycemia, and incident diabetes are distinct outcomes. To assess causal and observational evidence linking sleep to adult insulin resistance and evaluate the metabolic effects of sleep-directed interventions. This targeted narrative review prioritizes adult human experiments, prospective cohorts, randomized trials, and evidence syntheses. Web-accessible bibliographic records and primary sources were searched on 7 October 2026, with targeted verification of selected intervention findings on 8 October 2026. Controlled sleep restriction and circadian misalignment can impair insulin action. Evidence for habitual long sleep, insomnia, and irregular schedules is predominantly observational. Autonomic changes, altered lipid availability, and energy balance provide plausible pathways; detailed molecular mechanisms remain partly preclinical. Sleep-extension trials yield inconsistent metabolic results. In a small trial of adults with overweight or obesity and insulin resistance, sleep increased but multiorgan insulin sensitivity did not improve detectably. Insomnia treatment improves sleep symptoms, whereas glycemic benefits remain uncertain.