The aim of this study was to assess the causal relationship between narcolepsy and anxiety using Mendelian randomization (MR) methodology.Our research applied a bidirectional two-sample Mendelian Randomization strategy to explore the linkage between narcolepsy and anxiety. Utilizing summary data from GWAS on both conditions, we primarily employed the inverse-variance weighted technique for our analysis. To evaluate heterogeneity and horizontal pleiotropy, we utilized tools such as the MR Egger method, the weighted median method, Cochran's Q statistic, and the MR Egger intercept.The analysis using the inverse variance-weighted method showed a clear positive link between narcolepsy and anxiety, with an odds ratio of 1.381 (95% CI: 1.161-1.642, p < 0.001). Tests for heterogeneity and horizontal pleiotropy, including MR Egger and IVW methods, indicated no significant findings (p-values 0.616 and 0.637, respectively, for heterogeneity; p = 0.463 for pleiotropy). Furthermore, no reverse causation was observed between anxiety and narcolepsy (odds ratio 1.034, 95% CI: 0.992-1.078, p = 0.111), with consistent findings across various analytical approaches.This research suggests a possible causal link between narcolepsy and anxiety disorders. The results illuminate this connection and advocate additional studies to elucidate the mechanisms involved and to identify effective interventions.Copyright © 2024 Elsevier Inc. All rights reserved.