| Abstract: | Continuous rotating shiftworkers temporarily working overtime slept at least once during the working hours of their night shifts. They worked at an electric power distribution plant in São Paulo (Brazil). In order to detect factors that could be associated with sleeping on the job, we compared those who slept (sleep group – S) with those who did not sleep (non-sleep group – NS) as to the number of night shifts, the average length of night shifts, the variability in night shift onset and offset times and the length of sleep episodes at home between consecutive night shifts. Data collection was based on dairies filled in by the workers for 30 consecutive days. For both S and NS groups, the number of night shifts for each worker varied from 5 to 9, no difference being found between groups. Individual means of night shifts length varied from 9.4 ± 0.3 hr to 14.2 ± 0.6 hr; they were significantly longer in the S than in the NS group. Night shift onset times were shown to be significantly more variable in the S than in the NS group, whereas offset times did not differ significantly between groups. Length of sleep episodes at home was not significantly different between groups. Workers who slept on the job were those who had longer working bouts and / or more variable night shift onset times. Differences among workers may be due to individual strategies to cope with a situation in which the work schedule included night shifts that were much longer than the established 8 hours, and with many changes in onset times from one night shift to the next. |
