The Adjustment to a Slowly Rotating Shift Schedule: Are Two Weeks Better than One?

Abstract

The Bureau of Mines is examining alternative rotating work schedules that are more conducive to the health and safety of mining shiftworkers. The question asked in this study is whether or not there is an advantage to working the second week of a two week cycle, as would be indicated by reports of more positive health, mood and sleep items on the second week as compared to the first week. Forty-two workers at a surface mine in the midwest filled out the Work, Food and Sleep Diary for four to six weeks. They rotated every two weeks going from days to nights to afternoons with all weekends off. The dependent measures were defined as 1) health: the daily frequency of reported symptoms 2) mood: based on a self-evaluation of four descriptors, ALERT, SLEEPY, GROUCHY, and RELAXED, 3) total sleep length and sleep quality. Results indicated that on the second week of the night shift workers reported significant improvements in all four mood descriptors for the second half of their shift. Also, sleep quality as measured by awakenings during sleep improved on the second week of the night shift. None of the variables showed a worsening on the second week of the night shift. These results do not support a “cumulative trauma” effect for the schedule studied in this paper. On the basis of this study it could be recommended that two week cycles are superior than one week cycles.