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Personnel working on North Sea oil/gas installations are exposed to remote and potentially hazardous environments, and to extended work schedules (typically, 14×12h shifts). Moreover, overtime (additional to the standard 84-h week) is not uncommon among offshore personnel. Evidence from onshore research suggests that long work hours and adverse environmental characteristics are associated with sleep impairments, and consequently with health and safety risks, including accidents and injuries. However, little is known about the extent to which long hours and a demanding work environment combine synergistically in relation to sleep. The present study sought to address this issue, using survey data collected from offshore day-shift personnel (N=551). The multivariate analysis examined the additive and interactive effects of overtime and measures of the psychosocial/physical work environment (job demands, job control, supervisor support, and physical stressors) as predictors of sleep outcomes during offshore work weeks. Control variables, including age and sleep during leave weeks, were also included in the analysis model. Sleep duration and quality were significantly impaired among those who worked overtime (54% of the participants) relative to those who worked only 12-h shifts. A linear relationship was found between long overtime hours and short sleep duration; personnel who worked >33h/week overtime reported <6h/day sleep. Significant interactions were also found; sleep duration was negatively related to job demands, and positively related to supervisor support, only among personnel who worked overtime. Poor sleep quality was predicted by the additive effects of overtime, low support and an adverse physical environment. These findings highlight the need to further examine the potential health and safety consequences of impaired sleep associated with high overtime rates offshore, and to identify the extent to which adverse effects of overtime can be mitigated by favourable physical and psychosocial work environment characteristics.

Original publication




Journal article


Accid Anal Prev

Publication Date





383 - 388


FIFO, Long work hours, Offshore day-shifts, Overtime, Sleep, Work environment, Adult, Humans, Male, Middle Aged, North Sea, Occupations, Safety, Sleep, Sleep Wake Disorders, Surveys and Questionnaires, Work Schedule Tolerance, Workplace