The urban way of life that affects the entire population before people, especially students, places high expectations and numerous obligations, so an integral part of an individual's daily life is stress, a state of the organism in which there is a threat of violating one's own integrity. Stress is something that all students encounter during their studies, and in an academic context it also affects the quality of students' sleep. Stress and sleep quality are constructs that have a significant impact on executive functions and components of working memory. In view of the above, it can be determined that various studies have established the connection between stress and sleep quality with measures of working memory, and the goal of this research was to determine the relationship between stress, sleep quality and working memory in a sample of students at the University of Zadar and thus contribute to a better understanding interrelationship of the mentioned constructs. The sample consisted of 71 undergraduate students of psychology at the University of Zadar, of which 88.7% were female students (N=63) and 8.5% were male students (N=6), while 2 participants were classified as "other" (2.8%) . The average age of the sample is 20.5 years, and the total age range of the participants ranges from 19 to 28 years. The working memory task was performed live, while the participants took a sociodemographic data questionnaire, the Stress Scale from the Depression, Anxiety and Stress Scale (Lovibond and Lovibond, 1995; Croatian adaptation Jokić - Begić et al., 2012) and the Pittsburgh Sleep Quality Index (Buysse et al. ., 1989) completed online. In accordance with expectations, a positive correlation between stress level and sleep quality was established; participants who scored higher on the stress scale also scored higher on the sleep quality scale, that is, they are worse sleepers. The results also showed that participants with a lower level of stress achieved better results in the working memory task compared to those with a higher level of stress, however the difference in working memory capacity between "good" and "bad" sleepers was not established.