At no time in the history of medicine has the emphasis on safe care been more pronounced than now. Spurred by high-profile reports by the Institute of Medicine (IOM) and sensational instances where the health care system has failed to provide even the most rudimentary safeguards of patient well-being, the profession and the public are demanding that we look at the systems we work in and eliminate as many barriers to safety as possible. One topic that resonates with the public is that of sleep loss and fatigue in health care providers. Lack of sleep and fatigue are really separate entities, but with considerable overlap. They most often exist together in the clinical settings in which physicians find themselves. Sleep deprivation can be acute and/or chronic, resulting from busy schedules, frequent interruptions in sleep cycles, or medical conditions. Fatigue is the other side of the same coin and results from emotional exhaustion, long stretches of work demanding high levels of performance, or chronic illness. Regardless of the longstanding traditions in medical training and practice, the public have an intuitive sense that someone who has worked for 36 hours straight or who routinely works 110 hours a week simply cannot reliably perform at peak effectiveness. Most people find the current residency rules of 80 hours a week to be beyond their own capability and know how bad they feel trying to do their jobs on less than adequate rest. Recent news magazines have spotlighted the state of chronic sleep deprivation, from
which much of the population suffers, and listed the negative effects on performance resulting from lack of sleep. Those who come to us for care are acutely aware of this issue and expect us to place their interests over our own. The negative effects of sleep loss and prolonged time on task are well recognized in aviation, trucking, railroads, the military, and other industries where legislation is in place to limit hours worked. As physicians, it becomes an issue of professionalism to inform ourselves about the effect of sleep loss and fatigue and ensure that our systems of care do not force individuals to work beyond their physiologic limits.

Despite the obvious conclusion that patients deserve a well-rested caregiver, the issue of how to achieve this goal is a complicated one. The logical conclusion is to limit the number of hours that physicians are allowed to work. In contrast, physicians are taught to value total dedication to the individual patient, regardless of the time of day or how many hours it takes. This sense of personal responsibility is thought to be essential to the best care that can be offered and is deeply embedded in the culture of residency and practice. Nevertheless, less altruistic forces are also at work in the current system; there is a strong economic incentive to see as many patients and do as many procedures as possible. Enforcing strict limits on working hours may have unintended consequences and not lead to safer care, but may increase risk due to frequent hand-overs, loss of continuity, decreased experience in residency, and possible restricted access to physicians with limited skills. Furthermore, focusing on time worked as the only metric may distract attention from other embedded safety hazards in the environment. As in every discussion in healthcare, the trade-off between cost and outcome needs to be factored into the equation of safe care. At the least, physicians should be aware of the role that sleep and the effects of sleep deprivation and time on task have on performance. Physicians should be able to apply strategies to their practice to help reduce the impact of less than perfect sleep habits.

No one really seems to know why animals on this planet sleep. Studies show that even fruit flies sleep and when they are deprived of sleep, they develop a sleep debt that will be made up at the next opportunity to sleep.¹ Sleep is a complex phenomenon where active processes occur that lead to the health of the organism. Experts have debated on what is essential about the sleep period. However, most agree that sleep is a period of repair and restoration of key functions such as wakefulness, energy expenditure, and learning. Researchers have described the architecture of sleep and identified several stages that occur in cycles of 90 to 120 minutes through the sleep period. Early cycles have more deep, or Stage 4, sleep than cycles later in the typical sleep period. Older individuals seem to spend less time in Stage 4 sleep, and therefore may have a harder time recovering from sleep loss. Contrary to popular belief, older individuals do not need less sleep. Disruptions in either the quantity or quality of sleep can lead to excessive daytime sleepiness and impairment in tasks that require vigilance and judgment. Although there is some variation in the number of hours of sleep needed, the consensus is that most of us need 7 to 9 hours of continuous sleep in each 24-hour period.² Despite claims to the contrary, there is almost no one who can sustain performance in the face of a chronic reduction in the number of hours slept per night. Likewise, sleep that is disrupted by frequent periods of arousal is associated with a decline in function. In addition to work schedules that deprive individuals of sleep or result in frequent interruptions, there are more than 80 medical conditions and countless medicines that can contribute to the impairment of sleep. Physicians are just as subject to these problems as is the population at large. Although there is considerable individual variation in the magnitude of the negative effects of sleep deprivation on performance, it is not reasonable to assume that physicians are somehow a selfselect group immune to the physiologic rules that govern sleep in the rest of humanity.

As soon as you awaken from sleep, you begin to build up a sleep deficit (see Fig. 67.1). This propensity to sleep is related to your baseline sleep conditions and influenced by the intensity of daily activity. In normal circumstances, as the day progresses, the pressure to sleep increases until the individual cannot sustain wakefulness under any circumstances. This homeostatic process can only be reset by a period of sleep. In addition, physiologic processes controlled by the brain come into play. Humans evolved on a planet with light and dark cycles. Artificial lighting and the need to function in a 24/7 manner are relatively recent additions to the human condition. As such, we are governed by the circadian rhythms hard-wired into our bodies. An endogenous rhythm of body temperature, hormonal output, and alertness lasting slightly longer than 24 hours persists, regardless of external influences such as work schedules or travel. Nadirs in these factors typically occur in the early afternoon between 3:00 PM and 5:00 PM, and in the early morning between 3:00 AM and 5:00AM (Fig. 67.1). The relationship and feedback mechanisms between sleep homeostasis and circadian rhythms are complicated but, suffice it to say, the combination of sleep deprivation and circadian rhythm disturbance can be additive in reducing the ability to perform complex tasks. For the individual clinician trying to manage his or her own performance in the face of demands that were not anticipated by evolutionary necessity, awareness of the inescapable limits of human performance is essential.