Workers' sleep quality as determined by shift system and demographic factors.

The present paper is based on the results of a study conducted to examine whether there are any differences in sleep quality between permanent day workers and rotating shift workers working under two- and three-shift systems. Influences of demographic variables such as subjects' age and experience on sleep were also explored. The subjects studied consisted of 125 permanent day workers, 125 fortnightly rotating two-shift workers, and 50 weekly rotating three-shift workers. The method of data collection was that of field study through questionnaire. The results show that, compared to the permanent day workers, sleep quality is poorer for the rotating shift workers and, between the two groups of shift workers, it is poorer for the three-shift workers. These findings imply that a discontinuous two-shift system (without night work) is more convenient than a continuous three-shift system (including night work).