Evidence-Based Guidelines for Fatigue Risk Management in Emergency Medical Services: A Step in the Right Direction Toward Better Sleep Health

Good sleep is critical for good health.

Epidemiological, clinical, and treatment studies provide strong support for this proposition. For instance, short sleep duration (i.e., fewer than 6 hours per night) is associated with increased mortality risk and other important health outcomes (1, 2). Insomnia is a risk factor for subsequent depression (3), and sleep apnea is a risk factor for cardiovascular disease (4, 5). Treatment of insomnia and sleep apnea not only improve sleep and sleepiness, but also comorbid health indicators such as depression symptoms and blood pressure (6–8).

The field of sleep medicine has often focused on the identification, diagnosis, and treatment of specific sleep disorders, but the impact of sleep on health goes well beyond these disorders. While sleep disorders affect discrete proportions of the population, sleep characteristics influence health for every person. One working definition of sleep health is, “A multidimensional pattern of sleep-wakefulness, adapted to individual, social, and environmental demands, that promotes physical and mental well-being” (9). Specifically, sleep health can be described by sleep characteristics or dimensions including its regularity or stability across nights; satisfaction or overall subjective quality; alertness during waking hours; timing of sleep during the 24-hour day; efficiency, which characterizes the amount of sleep relative to the amount of time in bed; and duration, or overall amount of sleep. These dimensions of sleep health can be remembered with the mnemonic RU SATED. Sleep health is also characterized by appropriate adaptation to the reality of external factors, including work schedules. Accumulating evidence suggests that, beyond sleep duration alone, each of these sleep health dimensions are individually associated with health risks (9). More importantly, aggregate or composite measures of sleep health are associated in a graded fashion with health risks (10).

Why is sleep important to health? Simply put, human beings are meant to sleep at night, to be awake during the day, and to follow regular 24-hour rhythms. These patterns are deeply instantiated in our biology, down to the genetic and molecular level. Sleep is regulated by a homeostatic factor, which increases our “sleep drive” as a function of sustained wakefulness, and by a circadian factor, which promotes alert wakefulness during daylight hours, and sleep during dark hours (11). Homeostatic sleep drive is marked by increasing extracellular adenosine levels in the forebrain, and by characteristic electroencephalographic (EEG) patterns (11). Circadian rhythms are orchestrated by the suprachiasmatic nuclei (SCN) of the hypothalamus, which are entrained to environmental light-dark signals via specialized photoreception pathways, and which regulate brain function and systemic physiology via neural and hormonal signals. Ultimately, circadian rhythms reflect rhythmic transcription-translation patterns among a set of core clock genes. These genes are expressed not only in the SCN, but in every cell and tissue of the body, where they exert profound influence on cellular functions (12). We now know, for instance, that circadian genes are directly involved in cellular metabolism (13, 14), and that disruption of circadian rhythms and sleep have profound effects on systemic metabolism. Just one week of sleep restriction to 4 hours per night induces reduces glucose sensitivity and increases food craving in healthy young adults (15). Thus, sleep and 24-hour patterns are not simply voluntary behaviors; they are built into our genes, and they influence biology on very fundamental levels.

Shiftwork and irregular work schedules serve as exemplars of how individual, social, and environmental demands can challenge optimal sleep health. Night shift work requires us to be awake when our biology prepares us for sleep, and to sleep when our biology prepares us for wakefulness. It should not be surprising, then, that night shiftwork is associated with reduced alertness on the job, as well as reduced duration and quality of sleep during the day (16). Given what we are learning about circadian rhythms and metabolism, it should no longer be surprising that night shift workers are also at risk for obesity and metabolic dysfunction (17, 18).

At the same time, certain professions simply demand 24-hour availability, and nowhere is that more evident than in emergency medical services. Childbirth and myocardial infarctions are examples of biological and medical phenomena that also have circadian rhythms, and in both cases, there rhythms peak during the nighttime and early morning hours (19, 20). Individual and social factors, including economic incentives, child care and family responsibilities, and the need to staff EMS agencies, also provide an impetus for night shifts and extended shifts. However, the need for atypical work hours exacts a toll. EMS workers report elevated levels of fatigue, poor sleep, and increased rates of health problems such as depression, obesity, and cardiovascular disease (21, 22). Traffic accidents and medical errors related to fatigue and shift work are further sources of concern (23).

What does the field of sleep medicine teach us about how to deal with these vexing problems? We can and should continue to screen EMS workers for sleep disorders, including obstructive sleep apnea (OSA) and insomnia. Evidence from other sleep and fatigue sensitive occupations, such as transportation and medical training, shows that work scheduling interventions can reduce fatigue, improve performance, and enhance safety (24).

However, the first step is to limit factors that we know can worsen sleep health, and to promote factors that can improve sleep health. This is precisely what the evidence-based guidelines by Patterson and colleagues begin to do (25). These guidelines are the result of a rigorous and well established process. The authors sought input from key stakeholders; devised a list of critical questions; systematically evaluated the available evidence; developed, discussed, and voted upon recommendations from that evidence; and sought critical input from an even wider group of stakeholders. The result is a series of specific, actionable recommendations built on existing knowledge not only from sleep and circadian science, but also from the human performance literature, and from experience in similar occupations that require sustained operations and shiftwork. The process of developing these recommendations has also pointed toward important knowledge gaps that must be filled by future research. Implementation of these guidelines will point toward additional challenges, but also toward potential solutions. Therefore, the guidelines must be seen as the first step of an iterative process in which feedback from the field will play a critical role.

Although we are not yet able to recommend an optimal pattern of shift schedules for EMS workers, we do know enough to make some general recommendations for optimizing sleep health. These recommendations are based on principles derived from the behavioral treatment of sleep and circadian disorders, which have a strong evidence base in their own right. Keeping in mind the RU_SATED acronym, EMS workers and agencies can work to achieve the following:

•	Regularity: A predictable pattern of sleep and wakefulness is preferable. Work shifts and sleep periods occurring at the same time each day should be “strung together,” as opposed to following an irregularly irregular pattern.
•	Satisfaction: The best quality sleep generally results from having enough time to sleep, but avoiding excessive time in bed.
•	Alertness: The key to alert function during waking hours is to get adequate sleep at night. Strategic napping, either preventative (before a shift begins) or operational (during a shift) can also improve alertness.
•	Timing: Sleep is best when it occurs at night. Overnight shifts that prevent sleep should be minimized. When possible, operational naps between the hours of 2:00 AM and 5:00 AM should be encouraged.
•	Efficiency: Sleep is generally most restorative when it is most efficient, i.e., when it occurs as a solid block with few awakenings. Sleep efficiency is inversely proportional to the amount of time in bed; as time in bed increases, sleep efficiency decreases. By the same token, sleep efficiency must be balanced against total sleep time; a high-sleep efficiency cannot fully compensate for an inadequate total amount of sleep.
•	Duration: Adults should strive for 7–9 hours of sleep per day.

The biological reality of circadian rhythms and sleep need mean that human beings are not well suited to continuous performance over 24 hours or for optimal performance in the middle of the night. However, the medical reality is that human beings need care at all times of day, including emergency medical care. The question is not whether night shift work and even extended duty hours are necessary for emergency medical services. They are. The question is how we can use our knowledge of circadian rhythms, sleep, and human performance to optimize provider performance, well-being, and safety, and the medical outcomes of their patients. This evidence-based guideline takes a critical first step toward addressing that question.