SECTION 4 - SLEEP AND HEALTH

Sleep and Safety

Background

Demands on human wakefulness and alertness through increased requirements for shift work , on-call and prolonged work hours, and increased use of time for waking activities, have resulted in more people being awake more of the time. Paralleling these increased demands has been a growing appreciation of the risks posed by fatigue . In this context, fatigue is defined as a reduced capacity for cognitive performance due to time-on-task, inadequate sleep, adverse circadian timing, or the interaction of these factors. Fatigue can adversely affect public health and safety, due, for example, to oil spills, truck, bus and automobile crashes, railroad and commuter train disasters, aviation accidents, power plant mishaps, and medical errors.

The National Highway Traffic Safety Administration (NHTSA) estimates that 100,000–150,000 motor vehicle crashes each year and 4 percent of all fatal crashes are caused by drowsy driving . Drowsy driving crashes have a fatality rate and injury severity level similar to alcohol -related crashes.

Risk factors for drowsy driving crashes include: late night/early morning driving, people with untreated excessive sleepiness, people who sleep 6 or fewer hours per day, young adult males (ages 16 to 24), commercial truck drivers, and night shift workers .

Recent reports from the National Academy of Sciences, Institute of Medicine , concluded that as many as 100,000 patient deaths per year may be due to medical errors. Based on surveys of medical residents and other information, it is widely believed that substantial numbers of these adverse events result from fatigue due to prolonged work hours and inadequate sleep among doctors and nurses.

These problems of sleepiness and fatigue , and the contributions of inadequate sleep and night work, to human error and accidents have high costs in both lives lost and economic impact. Options, therefore, for mitigating sleepiness and fatigue need to be explored. The Department of Transportation (DOT) is investing significant resources to better understand and manage fatigue in transportation systems. For example, r ecent research supported by the Federal Motor Carrier Safety Administration suggests that both work schedules and sleep disorders are primary contributors to fatigue and sleepiness among truck drivers . Long and irregular work schedules that require operators to juggle work demands with family and social demands lead to reduced or disrupted sleep and, therefore, to fatigue.

E xcessive fatigue and its risks are largely preventable when the causes are identified and mitigated. For example, establishing cost-effective techniques for identifying and treating transportation workers (such as commercial truck drivers ) who have Sleep-Disordered Breathing (SDB) could lessen the likelihood of fatigue-related accidents. Preventing cumulative sleep debt by providing adequate recovery sleep opportunities for workers could reduce the risks of fatigue-related performance failures and catastrophic outcomes in many industries. Moving school start times to a later hour for adolescents could reduce the likelihood of drowsy-driving automobile crashes and injuries in school activities in this at-risk group. Finding ways to prevent fatigue-related medical errors by physicians and nurses could save thousands of patient lives each year, and improve the learning and safety of the doctors and nurses.

Although ensuring public and personal safety through adequate sleep is a broad issue of interest to many Federal, State, and private entities, the National Institutes of Health have a unique role in ensuring that scientifically sound evidence is acquired on the basic biomedical and health-related factors mediating sleep need, behavioral alertness, and risk.

Progress in the Last Five Years

•  Scientific evidence increasingly demonstrates that fatigue is a significant causal and contributing factor to adverse events including motor vehicle and other fatigue-related accidents. However, there is no general consensus that these data are definitive and compelling.

•  Field and simulator studies in safety-sensitive occupations (e.g., medical and surgical residents , truck drivers , airline pilots ) have demonstrated that performance in real-world tasks degrades under conditions of partial sleep loss and night work. Such studies highlight that the biology of neurobehavioral deficits from sleep loss and fatigue is not dependent on one's profession, motivation, or compensation.

•  Experiments have demonstrated that chronic reductions in sleep duration by healthy adults result in cumulative deficits in basic neurobehavioral functions, including vigilance performance, cognitive speed and accuracy, short-term memory , and executive functions. Such data are vital to establishing reliable, evidence-based recommendations for sleep need.

•  Research has identified some technologies that can detect fatigue and drowsiness before they result in a serious performance error. Some of these technologies include biobehavioral and physiological assessments, but few have undergone rigorous double-blind validation in controlled experiments.

•  Mathematical models of the regulation of sleep have been extended to predict waking performance capability based on sleep history, circadian phase estimates, and additional behavioral and biological variables. There is considerable belief that such models can be used to precisely identify schedules that minimize fatigue .

•  Recognition that fatigue -related errors and accidents are inherent in 24/7 operations has led to fatigue management using countermeasures that are preventive (e.g., education about the biological basis of fatigue) and operational (e.g., naps in the workplace). These fatigue management interventions have only recently been developed, however, and have not yet been widely studied to determine the extent to which they will be effective.

•  Work-related sleep loss and fatigue in medical professionals, particularly during training , has until recently received little attention. There have been relatively few controlled studies that have examined the impact of sleep loss and fatigue in the medical setting, and many published studies are methodologically flawed. The consequences related to sleep loss and shift work among physicians and nurses include effects on performance of professional duties, learning and memory , personal health and family consequences, and safety and liability. While the issue of work hours for physicians and nurses is currently being debated nationally, there remains a need for research to elucidate the effects of education and training of physicians and nurses in sleep and fatigue management.

Research Recommendations

•  Identify the effects of varying amounts of time for sleep, rest, and recovery (e.g., days off) on biological and behavioral resilience to fatigue- inducing work schedules. One of the most contentious but least well-understood features of fatigue and its consequences for safety concerns the role of recovery days off work. There are very limited data on the chronic (over weeks and months) effects of inadequate recovery opportunities outside the circadian cycle. There is a need to establish time-constants for fatigue buildup as a function of different recovery opportunities. Another need is to identify ways to scientifically design and evaluate work schedules that prevent the accumulation of excessive fatigue by allowing restorative sleep at reasonable intervals.

•  Establish the validity and reliability of innovative biobehavioral technologies and monitoring techniques that can detect drowsiness, fatigue and sleep propensity in medical and other workplaces. As devices predicated on detecting changes in the biology of wakefulness, these technologies have great potential. To be used effectively as either diagnostic devices or safety devices, however, they should meet rigorous standards for determining whether what is being measured is related to the neurobehavioral deficits induced by sleepiness and fatigue.

•  Establish the biological benefits for brain function, performance, and safety of nap sleep interventions (number of naps , their durations and circadian timing) as a sleep loss countermeasure and fatigue management strategy. Increasingly, 24/7 industries permit opportunities for naps in the workplace (e.g., sleeper berths on trucks, bunks on airplanes, sleeping areas on trains, on-call rooms for residents). There is a need for laboratory, simulator and field experiments on nap sleep physiology and waking neurobehavioral functions to establish the effectiveness of naps used repeatedly as countermeasures. There are many experiments on naps in response to acute sleep loss, but few that determine whether chronic use of naps or split sleep opportunities can effectively maintain waking neurobehavioral functions. If optimal napping strategies can be found to manage sleepiness and its neurobehavioral effects, this can form a basis for evaluating evidenced-based model fatigue management to determine the extent to which fatigue-related neurobehavioral deficits and risks can be reduced.

•  Assess the impact of sleep loss and fatigue in the context of medical training , including quality of patient care and patient safety/medical errors, learning and memory in medical education, and the health and well-being of resident physicians (motor vehicle crashes , mental health, etc.). Evaluate the effectiveness of fatigue management educational programs in improving the health and well being of medical trainees, including evaluation of the effectiveness of controlled countermeasures (napping, caffeine , etc.) and evaluation of the impact of "systemic" interventions (work hour restrictions, "night float" etc.) on sleep loss, performance, and medical errors.

•  Develop cost-effective methods to screen populations working in safety-sensitive occupations to identify those who are most likely to have sleep disorders that produce excessive sleepiness and performance-impairing risks. A major impediment to removing the risks posed by sleepiness due to unrecognized sleep disorders in the workplace is the lack of valid, simple, cost-effective tools for identifying who is most likely to benefit from a full evaluation. Such tools are needed, however, to enable physicians to certify that people in specific safety-sensitive occupations are fit to perform their jobs safely.

•  Develop novel techniques to facilitate worker acclimation to therapeutic interventions and effective use of therapies for sleep disorders (e.g., CPAP adherence). It is not sufficient to diagnose and to treat workers without a treatment compliance program in place.

•  Perform studies on the effects of chronic pharmacological enhancement of wakefulness in healthy persons on biology, behavior, and safety. This should extend from unregulated stimulants (e.g., caffeine ), to regulated stimulants (e.g., amphetamines), and novel wake-promoting substances. These studies should include identification of long-term effectiveness, side effects, and complications of use and abuse.

•  Assess the extent to which educational programs on the biological basis of fatigue , and mitigation of the performance deficits produced by it, are (1) effective in facilitating improved sleep, alertness, and the use of fatigue countermeasures, and (2) result in reduced risks of adverse events due to sleep loss and circadian biology.

•  Determine the extent to which mathematical models of waking performance capability (relative to dynamic interactions of sleep and circadian biology) can be used to precisely identify and develop work-rest schedules that minimize fatigue . Although efforts have been underway to identify the strengths and weaknesses of such computational models, more research is needed to ensure they accurately reflect the underlying biology of circadian rhythms and homeostatic sleep need as they pertain to work-rest schedules.