Improving sleep quality for rotating shiftworkers
by Katherine McNamara
Market volatility in the oil sector has led to a trend towards lean staffing and just-in-time scheduling over the last decade, resulting in work intensification and high overtime rates among hourly workers. The 24/7 operations at oil refineries require continuous coverage of nights, weekends and holidays, adding hardship to this demanding work schedule. Process operations at refineries are typically staffed by rotating shiftworkers, most of whom transitioned to two 12-hour shifts on rapid rotation schedules in the 1990s. The 12-hour shift, originally proposed as a compressed work week, provides little recovery time when an additional shift or two is added each week. How have these schedule changes influenced worker health and well-being? We surveyed oil refinery operators and technicians represented by the United Steelworkers to investigate this.
We identified high rates of sleep disorders in our surveyed population, as measured with the Pittsburg Sleep Quality Index (PSQI), a validated assessment tool. Nearly 80% of the study population reported PSQI scores indicative of sleep disorders, with 35% reporting severe sleep disorders. These scores are higher than have been previously reported for shiftworkers and rotating shift workers.
As sleep quality decreased, we saw increases in anxiety, depression, and gastrointestinal problems. Better sleep quality was associated with certain lifestyle characteristics (higher frequencies of exercise and leisure activities, shorter commutes), and work factors (more years of work history, staffing availability, access to time off, and lower job stress).
Sleep durations were shortest following shift transitions, averaging less than 5 hours; just over 5 hours were reported between consecutive night shifts. This improved to more than 7 hours after a day off. Shorter sleep durations were seen among workers with longer commutes, overtime hours at the end of a shift (holdovers), and added overtime shifts.
Day shifts started early: 5 AM was most common, but start times as early as 3 AM were reported. Longer sleep duration and better sleep quality were found among those with later start times. Previous research has demonstrated that early rising times and early start times are not accompanied by earlier bed times, resulting in chronic sleep debt.
Natural sleep schedules on days off were used to estimate chronotypes (i.e. morningness or eveningness). The majority of those surveyed were earlier than average chronotypes, but a cluster of late chronotypes were also observed among respondents. These individuals could be good candidates for permanent night shifts. One of the arguments for rapid shift rotations is chronotype flexibility, thought to facilitate shiftwork adaptation. But the high prevalence of very early chronotypes found here could indicate the opposite: chronotype inflexibility, or adaptation to early start times and difficulty adjusting to night shifts. The majority of those on night shifts exhibited severe chronotype misalignment according to their daily sleep logs.
These findings point to some possible interventions that could improve sleep quality in this safety sensitive population. Later start times, fewer shift rotations, and eliminating holdovers (particularly on 12-hour shifts) are recommended. Accommodating individual chronotypes in schedule assignments, in addition to maintaining access to time off and longer recovery periods, all have the potential to minimize the disruptions of this demanding schedule and improve sleep.
Article Details
Shift Work and Sleep Disturbance in the Oil Industry
Katherine A. McNamara, Wendie A. Robbins
First Published February 16, 2023 Research Article
DOI: 10.1177/21650799221139990
Workplace Health & Safety
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