Aims: In this definitive cross-sectional survey study, it has been aimed to research the effect of nurse workload increase on degradation of the sleep quality and daytime sleepiness.Methods: 204 volunteer nurses who work in Trakya University Faculty of Medicine Hospital clinics have attended to this study. In the survey , TISS-28 (Therapeutic Intervention Scoring System-28) for workload, Epworth Sleepiness Scale for evaluating the sleepiness and Pittsburg Sleep Quality Index have been used. TISS28 scale data has been divided into 4 sub-groups and compared to the rates it has got from the Epworth Sleepiness Scale and Pittsburgh Sleep Quality Index and a meaningful relationship between them has been looked for.Results: In relation to workload nearly half of the cluster (n:82) can be seen in the 2nd sub-group (p<0.05). We can accept that general nurse population spends a standart shift. In addition, there is a distinct statistical relationship between the degredation of sleepiness( Pittsburgh and Epworth) with the increase in the nurse workload(TISS-28). Conclusion: The increase of the nurse workload causes the degradation of the sleep status ad worsens the rested status. The degradation of the rested status and the sleep routines of the nurses, threats their health in the physical and mental way and on the other hand reduces the work effectiveness in the hospitals and causes a lot of stress and the other stress related problems in the work areas. In order to prevent this, the work condition of the nurses should be improved, their shift hours and workloads should be adjusted so as to not to disrupt their sleep status