Background. Sleep complaints are common in patients with epilepsy (PWE). Excessive daytime sleepiness (EDS) is one of the most reported complaints and its impact is still a matter of debate. Objective. Evaluate the relationship between EDS and epilepsy, with emphasis on prevalence, assessment, and causes. Methods. A systematic review on PubMed database in the last 10 years (2002 to 2012). The search returned 53 articles and 34 were considered relevant. After citation analysis, 3 more articles were included. Results. Most studies were cross-sectional and questionnaire based. 14 papers addressed EDS as the primary endpoint. 14 adult and 3 children studies used subjective and objective analysis as methodology. The number of studies increased throughout the decade, with 21 in the last 5 years. Adult studies represent almost three times the number of children studies. EDS prevalence in PWE varies from 10 to 47.5%. Prevalence was higher in developing countries. Conclusion. EDS seems to be related more frequently to undiagnosed sleep disorders than to epilepsy-related factors, and although it affects the quality of life of PWE, it can be improved by treating comorbid primary sleep disorders.