Background: Sleep is an essential need of humankind; it is necessary for quality of life and health at all ages. Poor sleep quality is closely associated with lifestyle habits including Internet use. This study aimed to evaluate the relationship between sleep quality and the level of Internet addiction among students at King Abdulaziz University (KAU). Methodology: This was a cross-sectional study carried out on July 2017 among 511 students aged 18-25 years enrolled at KAU in Jeddah, Saudi Arabia. The Pittsburgh Sleep Quality Index (PSQI) was used to evaluate sleep quality and habits, and Young's Internet Addiction Test was used to assess Internet addiction among students. Frequencies, chi-square, Pearson's correlation coefficient and multivariate analysis were used in data analysis. Results: A total of 511 students participated; 350 (68.5%) were women. Poor sleep quality was found in 54.4% of the participants, whereas Internet addiction was found to be mild in 42.3 %, moderate in 29.9%, and severe in 1.8%. A significant correlation was found between sleep quality and Internet addiction (p = .00). Other significant associations linked the quality of sleep to smoking and caffeine consumption. Conclusion: Sleep problems and poor sleep quality among KAU students were related to high Internet use. Further studies are needed to fully understand the factors that affect sleep behavior and Internet addiction among university students in Jeddah.