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Effectiveness: 1 Star Cost: Varies
Use: Unknown
Time: Medium

Overall Effectiveness Concerns: This countermeasure has not been systematically examined. There are insufficient evaluation data available to conclude that the countermeasure is effective.

Chronic medical conditions and sleep disorders compromise sleep and elevate feelings of fatigue (Smolensky et al., 2011). Three disorders, in particular, can cause drivers to fall asleep at the wheel:

  • Insomnia is the subjective experience of having difficulty falling asleep or staying asleep. It affects an estimated 11% of the U.S. population (NSF, 2008). People suffering from insomnia often report daytime sleepiness that interferes with their daily activities.
  • Sleep apnea is a breathing disorder characterized by brief interruptions of breathing during sleep, perhaps as many as 20 to 60 per hour (NSF, 2009a). By fragmenting nighttime sleep, sleep apnea produces daytime sleepiness. NSF estimates that about 4% of men and 2% of women are affected by sleep apnea. It can be treated by physical or mechanical therapy or by surgery.
  • Narcolepsy is a disorder of the central nervous system’s sleep-wake mechanism that can cause narcoleptics to fall asleep suddenly at any time (NSF, 2009b). It is quite rare, affecting about one person in 2,000. It can be treated with medications.

Several studies suggest that people suffering from insomnia are 2 to 3 times more likely to be involved in motor vehicle crashes compared to those without insomnia (Smolensky et al., 2011). Similarly, research also shows that people with sleep apnea are up to 6 times more likely to be involved in crashes (Teran-Santos et al., 1999). It has been estimated that crashes among people with sleep apnea cost approximately 16 billion dollars each year (Sassani et al., 2004). The number of crashes resulting from narcolepsy is not known.

Most cases of sleep apnea or narcolepsy are undiagnosed and untreated (Stutts et al., 2005, Strategy D6; NHTSA, 1998). Indeed, falling asleep at the wheel may be one of the main ways to raise the possibility of a sleep disorder and motivate a driver to seek medical attention (NHTSA, 1998). Once treated, people with sleep apnea have crash rates that are no higher than the general population (George, 2001).

There are many other medical conditions that can potentially compromise sleep or increase daytime feelings of fatigue such as asthma, chronic obstructive pulmonary disease, and rheumatoid or osteoarthritis. For a review of medical disorders and conditions that may affect sleep and driving risk, see Smolensky et al. (2011).

Many common prescription and over-the-counter medications can also cause drowsiness. One study of the sedative zolpidem[1] by drivers 70 and older in Alabama found increased at-fault crash rates in women and drivers 80 or older when compared with non-users (using adjusted rate ratios). Similar patterns were also observed for adjusted 5-year crash rate ratios (Booth et al., 2016). Warning labels on the medications note this and caution users against driving or other activities that could be affected by drowsiness. For more information about how medications can impair drivers, see the Alcohol- and Drug-Impaired Driving chapter, Section 7.3.

The principal countermeasures to address sleep apnea, narcolepsy, and medication effects are (Stutts et al., 2005, Strategy D6):

  • Communications and outreach on sleep disorders to increase overall awareness of their symptoms, consequences, and treatment.
  • Efforts with driver licensing medical advisory boards to increase their awareness of these conditions as they review driver fitness for licensing.
  • Efforts with physicians to increase their awareness of these conditions and their potential effects on driving, to treat these conditions as appropriate, and to counsel their patients to take steps to reduce the risk of drowsy driving.

Additionally, it is important that pharmacies and drug makers include patient education about the potentially impairing effects of certain medications on driving (Smith et al., 2018; see also the Alcohol- and Drug-Impaired Driving chapter, Section 7.3). Prescription labeling by drug makers as well as incorporation of electronic prompts when dispensing medication can be other promising opportunities for patient education (Smith et al., 2018). One survey study found that while pharmacists generally provide warnings on sedatives and narcotics to many patients (about 85% of 7,405 people surveyed), fewer people receive warnings on antidepressants (62.6%) and stimulants (57.7%) (Pollini et al., 2017).

Use and Effectiveness: There is no known information available on how frequently these countermeasures are used or on how effective they have been in raising awareness, increasing knowledge, or affecting behavior. NHTSA recently developed an OTC/prescription driving prevention initiative that is available at

Costs: Targeted communications and outreach to drivers (through driver licensing handbooks or flyers in license renewal material) or to physicians (through medical associations) would be relatively inexpensive. Communications and outreach campaigns directed at all drivers are expensive to develop, test, and implement. See the Alcohol- and Drug-Impaired Driving chapter, Section 5.2 and the Seat Belts and Child Restraints Chapter, Sections 2.1 and 3.1, for additional discussion.

Time to implement: Either targeted or general communications and outreach will require at least 6 months to plan, produce, and distribute. Efforts with driver licensing medical advisory boards could be implemented quickly.


[1] Brand name Ambien, among others.