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Volume 15 No. 07
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Accepted Papers

REM: A Publication for Residents and Fellows

Drowsy Driving Considerations in Non-Commercial Drivers for the Sleep Physician

Anand Bhat, MD1; Ann Marie Marciarille, JD2; Damien Stevens, MD1; David G. Ingram, MD3
1Division of Pulmonary, Critical Care, and Sleep Medicine, University of Kansas; 2School of Law, University of Missouri-Kansas City; 3Division of Pulmonary and Sleep Medicine, Children's Mercy Hospital


The sleep physician faces many challenges in the assessment of drowsy driving. The following article reviews current clinical evaluation methods and legal considerations at the state level in the United States.


Bhat A, Marciarille AM, Stevens D, Ingram DG. Drowsy driving considerations in non-commercial drivers for the sleep physician. J Clin Sleep Med. 2019;15(7):1069–1071.


The sleepy driver represents both a legal and medical conundrum for physicians in the United States. Sleepy drivers account for an estimated 16.5% of fatal crashes and 13.1% of crashes leading to hospitalizations.1 The American Automobile Association Foundation placed dashboard cameras in participants' own cars and found 9% of crashes involved drowsy driving.2

One study calculating rates for automobile accidents due to sleepiness found the proportion of individuals with sleep-related accidents was 1.5–4 times greater in the hypersomnolent patient groups than in the control group. studies found an increase in the odds of both accidents (odds ratio: 3.1, P = .01) and sleep-related accidents (odd ratio: 8.7, P = .01) in patients with narcolepsy or idiopathic hypersomnia and a crash rate double that of controls over a 5-year period.3,4

This perspective will focus on legal issues related to assessing drowsy driving in non-commercial drivers for the sleep physician as it represents the most common clinical scenario for the sleep physician.


A clinical assessment includes reviewing a patient's medical, occupational, sleep and psychiatric history. Many medical conditions increase the risk of daytime sleepiness either because of the disease itself or the medications used for treatment. Occupations requiring shift work have a higher risk of sleep disorders due to insufficient sleep or shift work disorder.5 A sleep evaluation, including any history of sleep disorders, self-reported sleepiness, and physical examination is also invaluable. This includes an assessment of sedating medications, lifestyle factors, insufficient sleep, circadian factors, and a history of sleep-related crashes or near misses. Finally, psychiatric conditions such as depression can disrupt the normal sleep pattern and increase the risk of excessive daytime sleepiness. Next, clinicians will then treat underlying medical conditions and counsel those with high risk behaviors. A polysomnogram may be ordered to assess for sleep-disordered breathing.

The Maintenance of Wakefulness Test (MWT) provides an objective assessment of the ability of an individual to stay awake. The current American Academy of Sleep Medicine guideline discusses indications but cautions that its predictive value for assessing real world accident risk has not been established.6 A physician should not solely rely on the mean sleep latency on the MWT to make a clinical decision. Mean sleep latencies less than 8 minutes on the 40 minute MWT are considered abnormal but mean sleep latencies above 8 minutes and below 40 minutes are of uncertain significance. In a study evaluating the association between MWT scores and performance on a driving simulator, a statistically significant increase in inappropriate line crossings was noted in the “pathologic group” with mean sleep latencies of 19 minutes or less.7 Another study of actual highway driving found that there were increasing numbers of inappropriate line crossings starting at MWT scores < 34 minutes.8 On the other hand, the MWT may not reflect real world alertness, given the passive nature of the test. Sleep deprived individuals have been shown to accurately signal self-related sleepiness to observers in a driving simulator but failed to signal 29% of the time in an MWT before falling asleep.9

Other laboratory testing such as driving simulators provide objective data but lack prognostic ability for on the road performance.10


Knowledge of state laws is important for physicians screening sleep disorder clinic patients seeking a non-commercial driver's license. Congress regulates long distance trucking and determines fitness standards under the interstate commerce clause of the Constitution.11 Federalism dictates that states have the authority to establish and enforce their own driving fitness laws for non-commercial drivers. Federalism implies that all powers not specifically delegated to the federal government are reserved to the states, and as such, federalism dictates that states have the authority to establish and enforce their own driving fitness laws for non-commercial drivers. As a result, drowsy driving laws differ by state (Figure 1). No state recognizes driving to be a constitutional right and all states limit driving to those with specific skills and willingness to comply with certain rules.12

Drowsy driving and lapse of consciousness laws by state.15


Figure 1

Drowsy driving and lapse of consciousness laws by state.

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The differences in laws reflect how legislators balance concern about drowsy driving as a public health matter versus excessively restricting the public's right to drive. As such, state requirements regarding physician reporting of drowsy driving significantly vary between states. Therefore, dual agency— when physicians both act as caregivers to patient-drivers and reporters to state government—represents a conundrum for sleep physicians.

It has been noted “[e]pilepsy is a paradigm disease that involves physicians as both caregivers to patient-drivers and consultants to regulatory authorities. Driving restrictions… protect the public safety but may interfere with personal freedom and livelihood.”13

Epilepsy is a disease with clearly defined events that lead to impaired driving. This is easier to report compared to drowsy driving which is not a medical diagnosis. It may be the byproduct of a variety of sleep impairments, including narcolepsy or sleep apnea. Drowsy driving is less about reporting a specific diagnosis than reporting a functional impairment based on the provider's understanding that impaired or dangerous driving may result. In addition, the physician dual agency involved with both treating the patient and alerting the authorities is less straightforward. This is something providers may not be, at present, particularly well-trained to ascertain. Also, providers may be reluctant to perform a risk assessment of drowsy driving, even if trained to do so, because of the concerns of dual agency.

California requires clinicians to report all diagnoses involving loss of consciousness to public health authorities. Public health authorities then report this information to the Division of Motor Vehicles where each report is assessed consistent with regulatory protocols. California removes the individual drowsy driving clinical encounter from the clinician and processes it through a public health and safety matrix which further screens for unacceptably drowsy drivers. This reform represents a possible solution to the conundrum of dual agency faced by the physician assessing the drowsy driver.14

In this review of the clinical and legal aspects of evaluating the drowsy non-commercial driver, many difficulties are encountered by the clinician. Lacking appropriate tools for assessment and an uncertain regulatory framework complicated by dual agency, the sleep community should research better assessment tools and advocate for regulatory regimes such as California's that remove the hazard of dual agency from the individual physician.


All authors have seen and approved the final manuscript. The authors report no conflicts of interest.



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US Const, art I, §8, cl 3.


Miller v Reed, 176 F3d 1202 (9th Cir 1999).


Berger JT, Rosner F, Kark P, Bennett AJ. Reporting by physicians of impaired drivers and potentially impaired drivers. J Gen Intern Med. 2000;15(9):667–672. [PubMed Central][PubMed]


Cal Code Regs. tit 13, §110.01, §110.02 (2014).


Summaries of Current Drowsy Driving Laws. National Conference of State Legislatures website. Published July 10, 2018. Accessed July 3, 2019.