Background: Neural phase synchronization is essential for coordinating communication across brain regions during sleep, and ischemic stroke may disrupt these collective neural dynamics. Objective: This study aimed to compare neural oscillator synchronization during sleep between healthy controls and patients with ischemic stroke using the Kuramoto model applied to polysomnography (PSG) data. Methods: Secondary EEG data from 150 healthy subjects and 97 patients with ischemic stroke were processed through quality control, signal preprocessing, delta-band filtering (0.5–4 Hz), phase extraction using the Hilbert transform, and calculation of the Kuramoto order parameter (r). Differences in mean synchronization and temporal variability across groups and sleep stages were examined using linear mixed-effects models. Results: After quality control, 147 healthy controls and 94 patients with ischemic stroke were included. Healthy controls consistently showed higher mean r values and greater temporal variability than the ischemic stroke group across N1, N2, N3, and REM sleep. Group, sleep stage, and group-by-stage interaction effects were significant for both mean r and its variability (all p < 0.001). Conclusion: Ischemic stroke was associated with reduced phase synchronization and more restricted neural synchronization dynamics during sleep. PSG-based Kuramoto analysis provides a quantitative framework for characterizing altered neural network dynamics after ischemic stroke, although differences between dataset sources and acquisition systems should be considered when interpreting the findings.