Sleep Deprivation and Fatigue
By Mitchell C. Sokolosky, MD, Associate Professor and Residency Director, Department of Emergency Medicine, Wake Forest University Health Sciences Center, Winston-Salem, NC; and Randall Best, MD, JD, Assistant Professor, Division of Emergency Medicine, Department of Surgery, Duke University School of Medicine, Durham, NC.
The dangers of sleep deprivation and fatigue can no longer be ignored. There is a large body of mounting evidence that demonstrates that fatigue impairs human performance. In fact, fatigue has been shown to have similar effects to alcohol intoxication.1 Fatigue may result in unintentional medical errors, motor vehicle crashes, mood disturbances, somatic complaints, and job burnout.2
Despite the fact that other high-risk industries (e.g., airlines) adopted restricted work hours decades ago to combat the negative effects of sleep deprivation and fatigue, the medical profession has only recently adopted similar restrictions for physicians in training. In 2003, the Accreditation Council for Medical Education (ACGME), the agency responsible for overseeing graduate medical education in the United States, instituted work duty hour restrictions for all U.S. residency programs.3 The rules limit the resident physician's weekly work hours, maximum continuous duty hours, and require at least one full day off duty each week on average. Although practicing physicians currently have no such restrictions on work hours, recent state legislation addressing the criminal effects of fatigue could affect sleep-deprived physicians.
Legal Consequences. Fatigue resulting from the long and irregular hours of health care shift workers has obvious harmful physical and mental consequences that are all too well known to emergency physicians and has been the subject of numerous scholarly articles and vigorous public debate.4 Less well known are the potential legal ramifications and effects of this problem. As first espoused in the Massachusetts Constitution and oft repeated, we are a government of laws and not of men.5 Once the public becomes aware of adverse effects of any social problem, legislation is sure to follow.
Most emergency physicians have heard of Libby Zion, the young woman who died after admission to New York Hospital in 1984, presumably from serotonin syndrome.6 As her distraught journalist father, Sidney Zion, investigated the circumstances surrounding her death, he was shocked to discover that the residents who cared for her had been working at the hospital for at least 18 hours. His efforts to draw attention to the long work hours of resident physicians led to widespread regulations limiting resident work hours.6 Ironically, it never was shown conclusively that her death was proximately caused by doctor fatigue; rather, an overwhelming workload or lack of proper supervision are equally plausible culprits.
Less well known, but similar in terms of the eventual legal ramifications, is the case of Maggie McDonnell. She was a 20-year-old New Jersey woman killed in 1997 by a driver who admittedly had been awake for 30 hours when he crossed the median and struck her vehicle.7
At his criminal trial, the driver was found guilty of mere careless driving rather than the harsher offense of vehicular homicide, and the driver received only a $200 fine.7 At that time, New Jersey law did not allow intentional and knowing sleep deprivation to fulfill the requisite mens rea or mental state necessary for a vehicular homicide conviction.7 Her family's grief, along with public outrage, led to "Maggie's Law," an amendment of the New Jersey vehicular homicide statute that provides that "proof that the defendant fell asleep while driving or was driving after having been without sleep for a period in excess of 24 consecutive hours may give rise to an inference that the defendant was driving recklessly."8
Thus, one who drives and causes a fatal accident knowing that he is sleepy or has been awake for a long period could be found guilty of the charge of vehicular manslaughter with resulting harsher criminal penalties than a charge of careless or reckless driving would bring. Analogous to the Libby Zion case, the focus of this tragedy was on the deleterious effects of driving while sleep deprived. The fact that the driver had been smoking crack cocaine prior to the accident was mostly overlooked, while public scrutiny honed in on the fear that dedicated, but fatigued shift workers could cause for deadly motor vehicle accidents.
A statutory law such as Maggie's Law has significant implications for all emergency physicians, not just resident doctors. Without a nap prior to an isolated night shift, an emergency physician easily could be awake for 24 or more hours. So far, New Jersey is the only state with a law such as Maggie's Law, but other states have considered it. In fact, a federal bill focusing on drowsy driving was introduced in the United States House of Representatives in 2002 and again in 2003, but each time it failed passage.9 Each of these bills focused on incentives for states and communities to develop traffic safety programs related to the problems of sleep-deprived drivers.
While criminal penalties for injuries caused by sleep deprivation might be justifiable, a more efficacious solution would combine a greater understanding of the physiologic effects involved and development of effective countermeasures to the problem.
Sleep Physiology. Sleep is a natural state of bodily rest that is necessary for survival. Sleep is a dynamic process of a complex series of sleep stages (stages 1-4 and REM [rapid eye movement]) that repeats itself several times throughout the sleep period. Sleep requirements change throughout life. However, the average person requires at least eight hours of sleep each day to be restorative. Long and short sleepers have been shown to have increased mortality.10 Sleep is regulated by the circadian rhythm (internal clock). The circadian rhythm is an approximate 24-hour cycle of reoccurring biochemical, physiological, and behavioral processes that are essential for life. Sleep loss is characterized as either acute, total sleep deprivation (recent 24-hour sleep loss) or as chronic, partial sleep deprivation (less than six hours of sleep per night on average for at least one week).
Neurocognitive Effects. The effect of sleep deprivation on cognitive performance has been well studied in sleep laboratories. Neurocognitive impairment is similar for both acute, total sleep deprivation and chronic, partial sleep deprivation. Performance testing of vigilance (responsiveness to simple repeated tasks) and serial mathematical calculations were equally affected by 24 hours of total sleep loss and one week of sleep restriction to five hours of sleep per night.11 Mean cognitive performance of young healthy adults who are sleep deprived (both short-term and chronic) are 1.3 standard deviations below the mean.12 Verbal processing and complex problem solving is impaired with acute and chronic, partial sleep deprivation.13 While most people recognize their limitations after acute, total sleep deprivation, the effects of chronic, partial sleep deprivation may go unrecognized. Even more worrisome is the fact that the effects of chronic, partial sleep deprivation are cumulative (sleep debt), and one cannot become acclimated even though many think they can. Adequate recovery sleep is necessary to correct sleep debt.
Clinical Implications. Recent studies have demonstrated the adverse effects of fatigue on patient care. Interns made substantially more serious medical errors when they worked frequent extended periods (24 hours or more) than when they worked shorter periods.14 Interns made 35.9% more serious medical errors, 20.8% more serious medication errors, and were 5.6% times as likely to make serious diagnostic errors when working extended work periods. Eliminating the extended work periods in an intensive care unit significantly increased sleep and decreased attention failures during night work hours.15 Night shift workers are particularly at risk. Total sleep time for emergency physicians on night shift duty are significantly less than their daytime counterparts.16 Performance also has been shown to decrease among night shift emergency physicians. Both completion time in a simulated intubation task and clinical accuracy in a triage task were worse for night shift physicians.17 Results appeared to be related to insufficient sleep and circadian rhythm disturbances.
Countermeasures. The most effective counter-measure to combat sleep deprivation and fatigue is simple: sleep. Adequate sleep is essential to healthy living and to being an effective physician. The goal is to come to work well rested and attentive. Clockwise shift schedules (e.g., days to evenings to nights) is preferable to counterclockwise schedules because of circadian effects.18 The timing of sleep for night shift workers is important to consider. Sleeping as soon as possible after a night shift is desirable. This allows for some sleep to occur during the normal sleep period. Splitting the sleep cycle (sleeping for 3-4 hours immediately after and before a shift) is acceptable for short stretches (a few days) following night shifts. The concept of "anchor sleep" (sleeping during the same period each day) is important to consider when working long stretches (weeks) of night shifts. A study performed on individuals in an isolation unit illustrates the effectiveness of anchor sleep.19 Individuals slept either as a single random eight-hour period or two randomly arranged four-hour sleep periods. Circadian rhythms were stabilized in the four-hour group if anchor sleep was taken at the same time each day regardless of the timing of the second half of the sleep as compared to the single random eight-hour group. Day sleep environments should be dark, quiet, and cool to facilitate adequate sleep. Naps are an effective countermeasure for combating fatigue. Naps as short as 20 minutes can be effective, but naps should not exceed two hours to avoid sleep inertia (period of drowsiness upon awakening).20 A nap taken before driving home may reduce the chances of an accident.21 Other effective countermeasures include the use of low-dose caffeine (avoid within four hours of sleep)22, aerobic exercise, and the use of bright lights during the circadian nadir (between 2 a.m. and 9 a.m.).23
Conclusions. Preparing for work by getting adequate sleep should be viewed by physicians as a professional responsibility to our patients. Fatigue may result in unintentional medical errors, motor vehicle crashes, mood disturbances, somatic complaints, and job burnout. The most effective countermeasure for fatigue is obtaining adequate sleep. We must obtain adequate daily (at least eight hours) and weekly recovery sleep (for sleep debt) as needed. We must understand our limitations when sleep deprived and plan accordingly. Fatigue must be viewed as an unacceptable risk with dire consequences to our patients and ourselves.
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