Background : This study was conducted to identify the sleep status of daytime workers who do not work in shifts. This study analyzed factors affecting sleep, including psychosocial stress. Methods : This study was conducted on 1,273 daytime workers at a manufacturing workshop. We used the Pittsburgh Sleep Quality Index to assess sleep and the Psychosocial Well-being Index Short Form to assess psychosocial stress. Regular health checkup was conducted for the worker’s clinical examination. Results : The mean sleep duration was 6.36 hours and the mean score on the Pittsburgh Sleep Quality Index was 4.46. Work type, Obesity and psychosocial stress were related to sleep duration. Age, sex, working period, obesity, psychosocial stress and musculoskeletal pain were significantly related to sleep quality. Researchers’ odd ratio for short sleep duration was 1.63 (95% confidence interval; 1.17-2.26), and the odds ratio of psychosocial stress high-risk group for short sleep duration was 2.65 (1.76-3.97). The odds ratio of those aged 50 years and over was 0.36 (0.17-0.77) and of those in their 40s was 0.45 (0.25-0.79) for poor sleep quality compared to those in their 20s. The odds ratio of the psychosocial stress high-risk group for poor sleep quality was 5.09 (2.74-9.48). The odds ratio of musculoskeletal pain group for poor sleep quality was 2.76 (1.64-4.64). Conclusions : Psychosocial stress was the large influential factor in the sleep duration and quality of daytime workers. In addition, musculoskeletal pain, age, and obesity were significantly related to the quality of sleep.