Purpose: This study aimed to examine the influence of anxiety and depression on sleep quality in adult epilepsy patients. Method: The convenience samples were used in 147 adult epilepsy patients who were being treated in one outpatient neurology clinic in Gyeonggi-do. Data collection took place from February 2018 to June 2018. The structured questionnaires included content of anxiety(K-BAI), depression(K-BDI-Ⅱ), and sleep quality(PSQI). Data were analyzed using SPSS 21.0 program. Specifically, descriptive statistics, frequency analysis, t-test, ANOVA, Scheffe’s test, Pearson’s correlation coefficient, and multiple linear regression were used. Result: The multiple regression analysis showed statistically significant result for stress level. Stress level was factor that affect sleep quality in the patients. Conclusion: This study found that factors affecting the quality of sleep in adult epilepsy patients was stress level. Therefore, it is necessary to develop a nursing intervention that manage stress of the patients while considering their general and health related characteristics in order to improve the quality of sleep.