Residency training is an essential part of medical education, characterized by long work hours, high cognitive demands, and insufficient sleep. Given the ACGME duty-hour reforms and the ongoing debate over work-hour restrictions, we conducted a scoping review on the relationship between sleep and clinical reasoning learning and performance in graduate medical education, using the Arksey and O'Malley framework (between 2003 and Dec 2024). Our review aimed to: (1) identify and map the existing literature linking sleep and clinical reasoning learning and performance in medical residents, (2) examine the methodological approaches used to assess sleep and clinical reasoning learning and performance, and (3) identify gaps in research to inform future studies. Studies were included if they studied physicians in residency training and examined both a sleep-related exposure (e.g. fatigue, sleep deprivation, shift work) and an educational outcome related to clinical reasoning (the cognitive steps up to and including establishing a diagnosis and management plan). We identified 4,309 articles initially, with 31 studies meeting final inclusion criteria, across a wide range of medical specialties. Clinical reasoning learning and performance assessments were heterogeneous, encompassing diagnostic accuracy, medical errors, decision-making speed, technical skill performance, and patient safety outcomes. Sleep measures varied, with most studies relying on self-reported sleep measures. Studies overall reported that insufficient sleep negatively impacts clinical reasoning learning and performance, particularly among junior residents. Residency programs should consider tailored evidence-based learning strategies and scheduling adjustments to ensure adequate rest, particularly for junior trainees.