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A Wake-up Call For Nurses: Sleep Loss, Safety, and Health

Authors: Laura A Stokowski, RN, MSFaculty and Disclosures


Sleepiness and Fatigue

Duty calls, and we answer. Often we do so whether or not we have had sufficient sleep. The alarm rings now to wake us up to the fact that working while fatigued or sleep deprived is not a good idea. It's time to change our collective attitudes toward work so that exhaustion and continued effort in the face of sleep deprivation are seen as posing unacceptable risks to patient safety rather than as signs of dedication.[1] Ann Rogers, PhD, RN, FAAN, Associate Professor, University of Pennsylvania School of Nursing, Philadelphia, is a well-known expert on the topic of sleep loss and sleep deprivation in nurses. Her presentation advanced our understanding about the nature of sleep and fatigue, and how the latter can jeopardize not only patient safety but our own health as well.[2]

Sleep is a basic human need. The busier we are, the more elusive and precious sleep becomes. Few of us are shy about vocalizing our need for more sleep to friends and coworkers, yet we rarely manage to get the sleep we crave. Like most Americans, nurses regularly shortchange themselves on sleep, getting by on an average of 6.8 hours of sleep on their work days instead of the commonly recommended 8 hours per 24-hour period. Ongoing sleep deprivation of as little as an hour a day can lead to a sleep debt over time that is not easily erased.[3] When we have a sleep debt, our inclination to fall asleep the next day increases. The larger the sleep debt, the stronger the tendency to fall asleep. Sleep debt does not go away by itself. Sleeping is the only way to erase sleep debt.

The terms sleepiness and fatigue are often used interchangeably, although they are not precisely the same thing. Sleepiness is the desire or inclination to sleep. Fatigue is the desire or disinclination to continue performing the task at hand. It is a weariness that can be caused by either mental or physical exertion. A person can be fatigued without being sleepy, but often the two go hand in hand, and their effects are very much the same.[4]

Reduced vigilance, reaction time, memory, psychomotor coordination, and decision making are the traits of the sleepy individual.[4] Speed of mental processing slows during the night under conditions of sleep deprivation.[5] In addition, the following signs and symptoms of fatigue are common:

  • Increased negativity and irritability, bad mood;
  • Inability to concentrate;
  • Lack of energy;
  • Short-term memory loss;
  • Apathy;
  • Poor communication; and
  • Perseveration on ineffective solutions.

Fighting the "Body Clock"

Thomas Edison is often blamed for our society's propensity to stay up late at night. Even the light bulb, though, can't keep us awake through the wee hours of the morning. The body's intrinsic circadian rhythm, controlled by the hypothalamus, coordinates daily cycles in such functions as sleep/wake, body temperature regulation, hormone secretion, digestion, performance capabilities, and mood.[6] Its role is to program us on a 24-hour schedule to sleep at night and to be awake during the day.

The circadian rhythm slows to its nadir between 0300 and 0500 and strongly favors sleeping during this time. Body temperature drops to its lowest. The feeling of being cold experienced by many nurses in the predawn hours is a sign of circadian disruption. Alertness and performance capabilities also drift downward.[6] It is not surprising that many nurses report struggling to stay awake and frequently falling asleep at work on the night shift.

Involuntary episodes of sleep lasting 10-20 seconds, known as "microsleeps," are common. Such brief losses of attention can appear to others as a blank stare, head snapping, prolonged eye closure, or failure to respond to outside stimuli when a fatigued person is trying to stay awake during a monotonous task. Often the person is not aware that a microsleep has occurred. Microsleeps occur most often during the circadian trough early in the morning, and they increase in frequency in persons who are sleep-deprived.

Another sleep-related phenomenon occurring during nighttime work hours is sleep inertia. Nurse practitioners who work 24-hour shifts and sleep in on-call rooms, as well as anyone who has attempted to nap during their break time, will have experienced sleep inertia if they managed to sleep longer than 30 minutes. Sleep inertia is the feeling of grogginess upon awakening from sleep that temporarily impedes one's ability to perform even the simplest of tasks. It often occurs when an individual awakens suddenly from a very deep sleep, and is more severe in individuals who have been sleep deprived. Sleep inertia typically lasts 15-30 minutes and can be reversed by activity, exercise, and noise.

Overall, night shift workers tend to get less sleep than their day shift counterparts, and their sleep is qualitatively poorer. Sleep during the day is shorter, lighter, more fragmented, and less restorative than at night; thus, the night nurse arrives at work with a larger sleep deficit than does a day shift nurse. Although some night nurses report that they are "night people" and have no difficulty sleeping during the day or staying awake at night, in reality, circadian rhythms cannot be reversed. Even those who have been working night shifts for many years are still programmed to sleep at night.

Fatigue and Impairment

Most nurses would never dream of going to work after having a couple of alcoholic drinks. The same nurses, however, might not think twice about pulling a double shift or going without sleep for as long as 24 hours. This is a common practice on the first shift of a night rotation or when a nurse practitioner works a busy 24-hour shift without getting any sleep. Alarmingly, though, studies show that when an individual has been awake for as few as 17 hours straight, their cognitive and psychomotor performance deteriorates to equal that of someone with a blood alcohol level of .05% (about 1-2 alcoholic drinks, depending on body weight and speed of consumption).[7]

After 24 hours of sustained wakefulness, one's impairment mirrors that of someone who has had 2-3 alcoholic drinks and whose blood alcohol is 0.1%, a level that is considered legally drunk in the United States. The finding that moderate levels of fatigue produce performance decrements that are greater than those induced by alcohol intoxication has been confirmed in other investigations.[8]

In sleep research, adult subjects who were restricted to 4 to 6 hours of sleep for 14 days showed steady declines in cognitive abilities, equivalent to going without sleep for 3 days in a row, as their sleep deficits accumulated.[3] Cognitive performance deficits included reduced abilities to pay attention, think and react quickly, "multitask," perform simple math problems, and avoid mistakes.

To prevent neurobehavioral deficits from accumulating, the average person needs slightly more than 8 hours of sleep per 24-hour period. There was no evidence that subjects adapted to the accumulating sleep loss, debunking the notion that individuals "get used to" chronic sleep deprivation. It is worrisome that subjects reported feeling only modestly tired during their most cognitively impaired moments, perhaps explaining why many people consistently fail to get enough sleep.

Fatigue-Related Errors

Although much evidence supports levels of fatigue-induced impairment sufficient to cause errors, little research has been done to document the occurrence of fatigue-related errors by nurses or nurse practitioners. In one study, nurses who worked rotating shifts were more sleep deprived and more likely to fall asleep at work; they were nearly twice as likely to report making a medication error when compared with nurses who predominantly worked day shifts.[9]

It is possible that the role of sleepiness as a factor contributing to adverse events and medication errors, particularly those occurring during the night shift, is currently underestimated. For example, root cause analysis of a serious 10-fold medication error taking place at 0400 in a neonatal intensive care unit did not include fatigue among potential contributing factors.[10] There is also some evidence that nurses don't acknowledge the role that fatigue might play in critical incidents. When intensive care and operating room nurses were questioned about error, stress, and teamwork, approximately 60% of them agreed with the statement that, "Even when I am fatigued, I perform effectively during critical times."[11]

Despite a lack of research linking fatigue among nurses and nurse practitioners to errors in patient care, there is a substantial body of research concerning fatigue-related performance degradation and error in other industries, such as aviation.[12] For example, 21% of incidents reported to the National Transportation Safety Board are attributed to pilot fatigue. There is no reason to believe that the nursing profession is immune to making fatigue-related errors. Both the Agency for Healthcare Research and Quality and the Institute of Medicine have highlighted fatigue and sleepiness as potential causes of medical and nursing errors in need of systems-based preventive solutions. In their 2004 report, "Keeping Patients Safe: Transforming the Work Environment of Nurses," the Institute of Medicine makes this recommendation:

To reduce error-producing fatigue, state regulatory bodies should prohibit nursing staff from providing patient care in any combination of scheduled shifts, mandatory overtime, or voluntary overtime in excess of 12 hours in any given 24-hour period and in excess of 60 hours in any given 7-day period.[13]

It remains to be seen whether state governments will adopt these recommendations limiting the work hours of nurses in the interest of patient safety. It is undoubtedly a difficult time for hospitals that are also facing a significant nursing shortage, and sometimes it is difficult to determine what is worse -- a tired nurse or no nurse at all? The fact that such recommendations have been made, however, might make it difficult for nurses to defend themselves in litigation involving errors that occur while working overtime hours or second jobs. These recommendations raise many questions about institutional and individual responsibility for adequate sleep and avoidance of fatigue.

Drowsy Driving

One of the most insidious aspects of fatigue is the inability of the individual to recognize his or her own level of impairment and to take appropriate action. Teri, a neonatal nurse practitioner, tells this story about driving home one morning after working a typical 24 hour shift:

"I was pulled over by a policeman, who told me that every trucker south of the city had called in to report me as a drunk driver. That's how badly I was weaving back and forth on the road."

Teri was lucky that she was stopped before she got into an accident and hurt herself and perhaps someone else. According to the National Highway Traffic Safety Administration, so-called "drowsy driving" causes 100,000 automobile crashes yearly, resulting in 76,000 injuries and 1500 deaths. Individuals who work night shifts have 6 times the risk of being involved in a sleep-related crash.[5] Nearly 95% of nurses working 12-hour night shifts report having had an automobile accident or near-miss accidents while driving home from work in the morning.[14]

Last year, the state of New Jersey passed "Maggie's Law," the first in the nation to specifically address drowsy driving. The law defines fatigue as more than 24 hours without sleep and allows prosecution of fatigued driving as recklessness under the state's existing vehicular homicide statute. Driver fatigue accident litigation could increase sharply, with both personal and corporate liability in cases where nurses and nurse practitioners are driving home after working 12- or 24-hour shifts.

Sleep Loss and Health

Chronic sleep deprivation also has important long-term health consequences for the individual, including an increased incidence of certain types of cancer. Working a rotating night shift at least 3 nights per month for 15 or more years may increase the risk of colorectal cancer in women.[15] The risk of breast cancer is significantly elevated among postmenopausal women who worked for 30 or more years on rotating night shifts, compared with those who never worked rotating night shifts.[16] It is hypothesized that increased nighttime light exposure produces an oncogenic effect through the melatonin pathway. Melatonin, normally secreted during the night, and thought to have cancer protective effects, is decreased in women who work the night shift.[16]

There is significant concern that the mismatch of circadian rhythm occurring on the night shift also increases the risk of cardiovascular disease by increasing the risk for metabolic syndrome.[17] The underlying cause of metabolic syndrome is insulin resistance, a lowered sensitivity in muscle, liver, and fat cells to the actions of insulin. Evidence indicates that night shift work is associated with increased insulin resistance.[18] Obesity, high triglycerides, and low concentrations of high-density lipoprotein cholesterol, all suggesting the metabolic syndrome, are seen in night shift workers more often than day workers.[17]

Although it is commonly stressed that 8 hours of sleep is optimal for good health, a recent study has contradicted this belief. Mortality risk was calculated for women in the Nurses' Health Study who answered a questionnaire about sleep duration in 1986. In this study, mortality was lowest among women who reported sleeping 7 hours per night.[19]


Sleep is a vital physiological function. Most adults do not get enough sleep, and the consequences of sleep loss can be serious. The delivery of healthcare relies heavily on human cognition and executive functions such as judgment, logic, complex decision-making, detection, memory, vigilance, information management, and communication. These are the processes that are most affected by the fatigue and sleepiness that result from sleep loss.

Where does this leave nurses, who can't avoid working the shifts that, from time to time, result in sleep deprivation and fatigue? Recent recommendations to limit the work hours of nurses aim to eliminate the threats to patient safety posed by fatigue and sleepiness in the workplace. While nurses do not wish to harm patients, they also don't want to abandon them when there are no replacement nurses after their shifts are over. Experienced nurses may feel that they are more likely to make mistakes from having to care for too many patients than from being a little bit tired at work. Simple mandates to limit nurses' working hours will not guarantee patient safety if adequate staffing levels are not simultaneously ensured.

Individual nurses need to protect their own health and safety as well as the safety of their patients. Professional nursing organizations should take the lead in setting the standards that will protect nurses both in and out of the workplace. If we fail to recognize and address sleep deprivation as a serious health issue, we may find our nursing shortage to be more acute than we predicted it would be.


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