Nearly 15 percent of all people working full time in the United States are shift workers. Shift workers suffer fatigue and poor performance as a result of their unusual work schedules, concludes a new study. Shift work includes not only the traditional night shift or rotating shifts, but also extended-duration (12-hour) shifts, and other nonstandard hours worked. In a review of their work and others, researchers at Brigham and Women's Hospital in Boston found that shift workers are impaired to various extents in four major physiologic determinants of alertness and performance, depending on their occupation. These four determinants are circadian phase or time of day, the number of hours awake, the duration of nightly sleep, and impaired performance upon waking (sleep inertia).
Abnormal working hours not only produce immediate effects on alertness and performance. Shift workers also suffer from significant short- and long-term health problems. Obesity, ulcers, cardiovascular disease, and cancer have all been linked to sleep deprivation and working during an adverse circadian phase. Shift workers are also at increased risk for daytime sleepiness and motor vehicle accidents. The researchers have a particular interest in health care workers. Their prospective, nationwide survey of 2,737 physician residents in their first year of training found that the residents were in the hospital 70.7 hours per week and they were sleeping for only 3.2 hours of that time. Each month, the residents were called to work 3.9 extended-duration work shifts (24 or more hours), with each shift averaging 32 hours.
The researchers propose designing work schedules around circadian rhythms and principles and eliminating extended work hours for medical interns. They also suggest the use of timed bright light, melatonin supplements, the use of caffeine and modafinil to promote wakefulness, and napping during extended-duration work shifts. The study was supported in part by the Agency for Healthcare Research and Quality (HS15906, HS12032, and HS13333).
See "Neurobehavioral, health, and safety consequences associated with shift work in safety-sensitive professions," by Laura K. Barger, Ph.D., Steven W. Lockley, Ph.D., Shantha M.W. Rajaratnam, Ph.D., and Christopher P. Landrigan, M.D., M.P.H., in the 2009 Current Neurology and Neuroscience Reports 9, pp. 155-164.
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