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The seemingly easy way to reduce drowsy driving crashes is to convince or require drivers to get enough sleep daily or arrange alternate transportation. However, getting more sleep may be a difficult goal. Drowsy driving may result from lifestyles that include insufficient or irregular sleep (shift workers, for instance) or from medical problems – issues beyond a driver’s immediate control. For example, a recent CDC study in 29 States found that people in certain occupational groups—production, healthcare support, healthcare practice, food preparation, protective services, and some transportation services—were more at risk for having short sleep duration of less than 7 hours each day (Shockey & Wheaton, 2017). Moreover, studies indicate that drivers themselves are poor judges of the performance decrements that result from drowsiness (Powell & Chau, 2011).

Behavioral strategies for drowsy driving focus on removing some of the underlying causes or promoting awareness of the risks. Currently, few studies have examined whether the standard behavioral countermeasures of laws, enforcement, and sanctions (which are used successfully for alcohol impairment, seat belt use, aggressive driving, and speeding) are effective for drowsy drivers. Additionally, standard behavioral countermeasures have been studied with young drivers. Some GDL provisions help reduce drowsy driving by prohibiting nighttime driving (see the Young Drivers chapter, Sections 1.3 to 1.5).

Drowsy driving that is related to a driver’s job may be reduced through employer policies and programs. Links to employer-based resources are available from the Network of Employers for Traffic Safety through The National Safety Council also provides resources to employers, including an online fatigue toolkit - The NTSB provides an overview of employer measures at Drowsy driving caused by medical conditions, such as sleep apnea, or by drugs or medications may be addressed through policies, communications, and outreach. Similarly, communications and outreach may be useful in raising awareness of specific drowsiness issues among certain high-risk populations. However, it is unknown if any of these strategies have been evaluated.

There are a variety of environmental and vehicular strategies to address drowsy driving. Rumble strips, both on the shoulder and the centerline, have demonstrated their effectiveness in preventing crashes associated with inattention or drowsiness (Persaud et al., 2016). Other roadway improvements, such as wide and visible edge lines, more easily visible road signs, and better lighting at night can help drivers who are not fully alert, particularly due to sleepiness. Vehicular strategies that hold promise for reducing crashes among drivers who are drowsy or inattentive include collision avoidance technologies such as lane departure warning, crash-imminent braking, and forward collision warning, and vehicle-to-vehicle and vehicle-to-infrastructure communications technologies (IIHS, 2012; IIHS, 2014). Such technologies, once available only in luxury brands, are now offered in many new vehicles. Additionally, in-vehicle technologies are available and being further developed to detect driver drowsiness by monitoring driver performance and then warning drivers (May & Baldwin, 2009; Papadelis et al., 2007; Sahayadhas et al., 2012; Brown et al., 2014). This chapter only addresses behavioral strategies. It does not include environmental, vehicular, and engineering countermeasures because State Highway Safety Offices generally do not have authority or responsibility in these areas.

Driver drowsiness is a critical issue for commercial drivers. About 14% of truck drivers reported a near-crash due to drowsiness according to a 2012 survey by the National Sleep Foundation (NSF, 2012). The Federal Motor Carrier Safety Administration, in partnership with Transport Canada and several Canadian Provinces, created the North American Fatigue Management Program (NAFMP) to research and educate against fatigued driving (FMCSA, 2016). FMCSA regulates drowsiness in commercial drivers through Hours of Service regulations, driver logs and inspections; starting December 2017, the use of electronic logging devices (ELDs) were made mandatory for commercial bus and truck drivers (80 Fed. Reg. 78292, 2015). NHTSA has also developed a prototype Drowsy Driver Warning System that appears promising in reducing drowsiness among drivers of heavy vehicles (Blanco et al., 2009; see also Brown et al., 2014). As with the environmental and vehicular countermeasures mentioned above, commercial driver countermeasures are not discussed in this guide because they generally do not fall under SHSO jurisdiction.