Countermeasures for Mitigating Fatigue in Motor Vehicle Operators

Abstract

Sleep debt and time of day/night (circadian rhythm) exert substantial effects on commercial motor vehicle (CMV) operator (e.g. truck and bus/motor coach, railroad engineer, aviation pilot) performance-and, therefore, safety. In this chapter, the influence of sleep debt and circadian effects on operator performance are described. Efficacy of various countermeasures is reviewed, and the influence of individual operator traits (genetic factors) is briefly discussed. It is concluded that sleep (napping) remains the best strategy for restoring and maintaining CMV operator neurobehavioral performance. Results from ongoing research will lead to occupation-specific and individualized strategies for managing sleepiness and fatigue in operational environments. T his chapter is focused on (a) operator sleep debt and (b) time of day/night during which the operator works as two main factors that exert substantial impact on operator cognitive performance and alertness. A variety of countermeasures have been proposed to mitigate operator performance deficits due to sleep debt and time of day, including caffeine, timed light exposure, sleep-promoting compounds, and napping strategies. Over the past several years, results from other lines of research show that the efficacy of these countermeasures is moderated by operator traits, including genetic differences. Following a brief description of how sleep debt and circadian rhythms impact cognitive performance and alertness, efficacy of various countermeasures is reviewed. It is appreciated that factors other than sleep debt and time of day impact cognitive performance and alertness (herein collectively referred to as "neurobehavioral performance") and that fatigue encompasses more than just neurobehavioral performance. We focus on sleep debt and time of day (circadian effect) because these serve as the backbone of many mathematical models (Mallis, Mejdal, Nguyen, & Dinges, 2004) used in fatigue risk management systems (Mallis et al., 2004). Also, efficacy of various countermeasures is commonly evaluated under conditions of increased sleep debt and unfavorable time of day, with neurobehavioral performance metrics serving as the critical outcomes. Other factors influencing fatigue are discussed in other chapters of this volume.

Diurnal and circadian variation of sleep and alertness in men vs. naturally cycling women

“…Indeed, sleep inertia is generally believed to be dissipated within that time frame (33). Controlling for both circadian phase and homeostatic sleep pressure using a forced desynchrony protocol, Scheer et al (34) demonstrated that the effect of sleep inertia on performance was gone within 20 min across all circadian phases.…”

Effects of Sleep Deprivation and Hazard Types on the Visual Search Patterns and Hazard Response Times of Taxi Drivers

“…Considering the characteristics of their long operation time and single working environment, it is possible to take a nap after a period of operation. It has been proven that stopping for a nap is effective in reducing the elevated risk of accidents associated with driving fatigue [42]. Second, the study found that sleep-deprived drivers had slower responses to covert hazards and took longer to fixate on covert hazards than the control group.…”

Genetic Markers of Differential Vulnerability to Sleep Loss in Adults

“…The efficacy of caffeine in attenuating neurobehavioral performance deficits induced by sleep loss has been well established [ 119 , 120 , 121 , 122 , 123 , 124 ]. Acute caffeine consumption (using doses from <80 mg to 600 mg) has been shown to mitigate performance declines in sleep-deprived individuals in a variety of domains, including on attention, memory, information processing, executive functioning, and driving tasks (reviewed in [ 125 ]).…”

“…Notably, caffeine becomes less effective at preventing performance declines as the pressure for sleep increases during extended wakefulness [ 4 ]. In addition, robust individual differences in response to both sleep deprivation and caffeine confound the effectiveness of this mitigation strategy [ 4 , 123 , 124 ].…”