[Interindividual differences in tolerance to shift work and characteristics of shift workers: relation between the quality and duration of sleep and certain worker characteristics].

The investigation aimed at examining the relationship between the quality and duration of sleep on the one hand and various shift workers' characteristics on the other, as well as establishing whether sleep characteristics were congruent with some other indices of night shift tolerance. A total of 604 rotating shift workers working in a fast rotating shift system were administered a battery of questionnaires. The results showed that sleep quality was related to their many characteristics, especially to neuroticism, rigidity of sleeping habits, flexibility of habits, and relaxedness. Actually, the shift workers' characteristics accounted for a notable percentage (48%) of interindividual differences in sleep quality. However, there were fewer traits related to sleep duration than to sleep quality so that only a small percentage of interindividual differences in sleep duration could be explained (12-30%). Sleep quality proved to be a good indicator of night shift tolerance. The results concerning sleep duration indicated only sleep duration on the afternoon shift and days off, as well as average sleep duration in the complete shift cycle, to be relatively good indices of night shift tolerance.