In 1998, nearly 30% of all fatal accidents involving large trucks occurred during hours of darkness, according to the Federal Motor Carrier Safety Administration's Large Truck Crash Profile : The 1998 National Picture). In about 1.5% of crashes involving large trucks, police reported that drivers visibly appeared to be fatigued or very tired. More than 7% of single-vehicle fatal truck accidents were reported as having driver drowsiness or sleeping as a related factor. The National Highway Safety Administration (NHSTA) reports that 56,000 automobile accidents per year are caused by drivers falling asleep at the wheel. According to the 1990 World Almanac, each accident involving a fatality or very serious injury results in a cost of nearly $1.5 million, simply accounting for wage losses, medical expenses and insurance administration. Humans are diurnal species, programmed to be awake during the day and asleep at night. Therefore, it is not surprising that sleepiness plays an important role in vehicles accidents. The most common preventive action taken by sleepy drivers is to stop driving, change the environment in the vehicle by opening the windows or turning on a loud radio, or consume caffeinated products. Although the preferred preventive action is to stop driving, it is known that this course of action does not always happen due to work demand. Light can, conversely, be used as a non-pharmacological treatment for increasing alertness at night and thereby possibly reducing sleep-related traffic accidents. Recent research has begun to illustrate the many ways that light and lighting systems affect humans in terms of circadian photobiology, including the characteristics of light necessary to regulate the circadian system. It is well established that light can increase alertness at night or shift the timing of one's sleep to daytime hours instead of nighttime hours. The present report summarizes this research with the objective of providing a framework for integrating circadian photobiology into transportation lighting practice. As will be discussed here, the application of light for impacting the circadian system can be a non-pharmacological tool to increase alertness and possibly reduce sleep-related accidents at night. A framework for future research needed to integrate knowledge of light's impact on nighttime alertness is also discussed. (Author/publisher)
Abstract