Aim:Daytime sleepiness is a condition that affects sleep quality, which is known to be associated with accidents. Detection of daytime sleepiness and related conditions in working life may be a fundamental step for taking early precautions in terms of shift organization in particular where shift work is being done. Aim: The aim of this research is to examine the effects of shift work systems on the sleeping, health and some personal habits of workers. Material and Method: The cross-sectional study of this study consisted of 431 people working in a thermal power plant in Zonguldak, and 354 people who met the sampling criteria. The data were collected through a questionnaire determining the socio-demographic characteristics, health status and characteristic of work-life (29 guestion), and Epworth Sleepiness Scale. Results: The majority of workers are men (98.3%). Average age 44.8±6.0. Looking at the shift distribution, 13.3% were on doubleshift; 42.1%, on triple-shift, and 4.6%, on regular daytime. 19.0% of the regular daytime workers, 11.0% of the double-shift workers and 70.0% of the triple-shift workers had an Epworth Sleepiness score of 10 or higher. Of all employees 28.3% had daytime sleepiness. Smoking prevalence in employees were 52.8% and 53.1% of the employees were consuming alcohol. Alcohol consumption (p= 0.024) and tea and coffee consumption (p= 0.040) were higher in workers with two or three shifts than regular daytime shifts. Conclusions: In working life, the relation between shift work and sleep is a stuation that is being examined. In this study, Double and triple shift workers’ daytime sleepiness score was found to be higher.