<p>Light pollution has been implicated in liver health. This study aimed to investigate the association between bedroom nighttime light pollution and the risk of hepatic encephalopathy (HE) in patients with hepatocellular carcinoma (HCC). A total of 454 HCC patients were enrolled from communities. Bedroom nighttime light intensity was measured using an illuminometer (lux) at baseline, 2 months, and 4 months. Sleep quality was assessed at these three time points using the Pittsburgh Sleep Quality Index. These data at different time points were averaged separately for subsequent analyses. All patients were followed up for 12 months from baseline (unless death occurred), and HCC-related adverse outcomes were recorded. Multivariate logistic and Cox regression were adopted for statistical analysis. The results indicated that higher mean bedroom nighttime light intensity (&gt; 50&#xa0;lx) was significantly associated with an increased risk of both overt HE and minimal HE. Furthermore, it was associated with impaired liver function, esophagogastric variceal bleeding, and elevated HCC-related mortality. Notably, interaction analysis revealed that age and TNM stage may modify the aforementioned associations to some extent. In conclusion, bedroom nighttime light pollution is linked to an elevated risk of HE and may represent a potential risk factor warranting future validation.</p>