Goals: A systematic review was conducted to evaluate the efficacy and safety of proton pump inhibitor (PPI) therapy in relieving nocturnal reflux symptoms and sleep disturbances. Background: Nocturnal gastroesophageal reflux disease (GERD) is commonly associated with sleep disturbances. The benefits of PPI therapy for GERD-related nocturnal reflux and sleep disturbance remain unclear. Study: We searched the MEDLINE, EMBASE, and Cochrane CENTRAL databases from inception to March 1, 2026, for randomized controlled trials (RCTs) in adults with GERD and sleep disturbances that compared any PPI to placebo or an alternative therapy. The primary outcome was the proportion of patients experiencing relief from nighttime heartburn. Secondary outcomes included relief from GERD-related sleep disturbances, changes in subjective sleep quality, work productivity, and treatment-emergent adverse events (TEAEs). Results: Five RCTs involving 1495 patients met the inclusion criteria. Three placebo-controlled trials consistently showed that PPI therapy improved nighttime heartburn relief and GERD-related sleep disturbances compared with placebo. Subjective sleep quality and sleep-related daytime functioning also generally improved with PPI therapy. However, the findings were more heterogeneous across trials because of differences in study populations, comparators, and outcome measures. Across the placebo-controlled studies, TEAEs were generally similar between the PPI and placebo groups. Conclusions: PPI therapy was associated with improvement in nighttime heartburn and reflux-related sleep disturbances, especially in patients with reflux-driven nocturnal symptoms. The available evidence also suggests potential improvement in subjective sleep quality and sleep-related daytime functioning.