Nowadays, shift work is a necessity. Unfortunately, according to many studies, it carries serious health implications, e.g. sleep disorders.To assess the prevalence and determinants of sleep disorders among shift workers compared with daytime workers.The study was conducted with use of a questionnaire, containing Sleep Quality Scale (SQS) and Epworth Sleepiness Scale (ESS) to assess sleep quality, as well as a set of open and closed questions concerning the factors that may interfere with sleep.Data have been collected from 286 individuals; 52.8% of shift workers (case group) and 47.2% of regular daytime workers (control group). There was a significant difference in the quality (SQS) of sleep (31.3 +/- 6.50 vs. 27.6 +/- 5.49) and the evaluation (ESS) of sleepiness (8.4 +/- 3.85 vs. 7.6 +/- 4.04) between the two groups. No significant correlations were found between the ESS and SQS values and reported sleep duration, age of respondents, marital status and napping on the job. The more the night shifts a month, the worse the respondents' quality of sleep (SQS). The employees pointed to irritability, depression, fatigue, emotional tension, impaired family and social life as a result of shift work.The prevalence of sleep disorders in the entire study population was high, with its considerably higher rate in the group of shift workers. Shift work causes disorders and emotional problems in family life noticeable by the subjects. It would be advisable to carry out training programs addressed to employees and managers in the field of sleep hygiene and activities that minimize the negative consequences of shift work.