SHIFT WORK DISORDER - myCME.com

Shift-work disorderFigure 1 Risk rate and periods of drivingRisk rate2.52.01.51.00.5“Normal hours of work”04-6 6-8 8-10 10-12 12-2 2-4 4-6 6-8 8-10 10-12 0-2 2-4am am pm pm amThe risk of a truck driver experiencing a traffic accident is high during times ofpostprandial drowsiness but is greatest outside normal working hours and, inparticular, at the end of the night.Reprinted with the permission of the publisher (Taylor & Francis Group, http://www.informaworld.com) from Ergonomics. “Lorry driver’s time habits in workand their involvement in traffic accidents,” by Hamelin P, January 9, 1987. 89found to be twice as high during a night shift than duringa day shift (OR, 2.04; 95% CI, 1.98-2.11). 83 The oddsof reporting an accident or error due to ES were twiceas high among nurses on a rotating-shift schedule comparedwith nurses on a fixed day or evening shift. 13Other workers with vital roles are also affected bythe demands of shift work. Police officers required towork shifts were reported to be significantly more likelyto experience a sleep-related accident at work or athome than were their non–shift-working colleagues(OR, 2.24; P < .0005); data concerning the types of accidentsexperienced by these police officers were notcollected in this study. 12More accidents are reported by workers commutinghome after the night shift than by day workers. 84,85For example, 40% of motor vehicle accidents experiencedby medical residents in their first postgraduateyear occurred during the commute home after shiftwork. 86 Moreover, 74% of motor vehicle crashes involvingemergency medicine residents occurred after theyhad worked a night shift, compared with 12% after a dayshift. 85 Among night-shift working nurses, 79% reportedexperiencing at least one episode of drowsiness on thecommute home in a 4-week study. 87Driving as part of a shift-based occupation alsopresents risks for accidents, with approximately 25%of police officers reporting that they have fallen asleepat the wheel while driving at work. 88 It is not surprisingthat the vast majority of single-vehicle accidents occurearly in the morning, when drivers are sleepiest 89,90(FIGURE 1).Early-morning sleepiness is also thought to beresponsible for the increased rate of military flight accidentsat this time of day. 91 Twelve percent of US AirForce non-aircrew shift workers admit that they have experienceda fatigue-related operational error, althoughonly 31% of those affected officially reported such anevent. Of concern, work/rest guidelines used by shiftworkingUS Air Force aircrew do not appear to greatlyimprove matters, as fatigue was found to be a factor in13% of serious aviation mishaps recorded between 1972and 2000. 92Although these data are illuminating, it is apparentthat very few studies have been published on the rateof accidents specifically caused by SWD. Consideringthat patients with SWD are particularly vulnerable tothe circadian issues created by shift work, it seems likelythat they must make up a significant proportion of theshift-working population that experiences work-relatedand traffic accidents. However, until further studies areperformed that specifically analyze accidents involvingpatients with SWD, we can only anticipate that theincidents that these individuals experience are moreharmful and occur more frequently compared with thegeneral shift-working population.Economic impact of SWDAs described in “Cognitive effects associated with shiftwork and SWD” on page S6 of this article, shift work isassociated with significant neurocognitive deficits andreduced efficiency at work. The costs due to lost productivityand accidents associated with shift workersperforming at suboptimal level are, therefore, likely tobe substantial. To date, studies of the direct and indirectcosts of shift work and SWD have not been published;however, an indication of the scale of the economicburden can be gained by looking at the costs associatedwith the 2 key symptoms of SWD: ES and insomnia.A study of the economic consequences of ES (performedusing 1988 data) reported that ES of any etiologywas responsible for motor vehicle accidents costingbetween $29 billion and $38 billion annually ($53 billionand $69 billion, when adjusted to 2009 values) andwork-related accidents (including deaths and disablinginjuries) costing between $10 billion and $13 billionannually ($18 billion and $24 billion when adjusted to2009 values). 93S January 2010 / Vol 59, No 1 • Supplement to The Journal of Family Practice