“House staff safety should no longer remain in our collective blind spot, but should receive the [same careful attention that we give to patient safety].”
In this issue of Anesthesiology, Huffmyer et al.1 present findings from a simulated driving study that supports an often-neglected goal of house staff duty hour rules—protecting the doctor from motor vehicle crashes due to drowsy driving. When comparing self-reports and simulator-measured driver performance after versus before six consecutive night shifts, they found (1) increased self-reported sleepiness, feeling less alert and less safe to drive; (2) difficulty in controlling the simulated vehicle to avoid collisions; and (3) worse reaction times and lapses in attention during the driving task.
As Huffmyer et al.1 state, “Residents in the night shift condition seemed to have consistently poor control of speed and lane position, especially at the beginning of their driving.” This is not surprising: consecutive night shifts cause not only sleep deprivation, but also circadian misalignment. Residents in the day shift condition also showed “degradation of control of speed and lane position over time.” Such deterioration in performance over time is characteristic of chronic sleep deprivation, a common state among house staff, and particularly salient for those with long commutes who must remain vigilant for sustained periods of time.
Individuals do not adapt to chronic, partial sleep deprivation. Rather, they accumulate sleep debt, which is associated with progressive declines in psychomotor vigilance task performance, even though the ability to self-rate sleepiness plateaus.2 Drowsy driving increases crash risk not only when the driver actually falls asleep, but also as a result of impairments in judgment, executive function, cognitive speed, and muscle coordination.3
The controversy over house staff sleepiness related to work hours is not new. Indeed, the death of Libby Zion in 1984 brought to public attention the long hours worked by residents, and the Institute of Medicine recommended duty hour limits,3 despite an inability to quantify the “relative proportion of errors attributable to” sleepiness versus other factors, such as supervision. Regulatory agencies now restrict duty hours, shift length, overnight call frequency, and the number of consecutive overnight shifts that house staff are permitted to work.
Restricting hours, though, results in more patient handoffs and less educational opportunities, which could compromise patient safety and house staff learning. Multiple investigators have evaluated the effect of duty hour restrictions on patient safety and house staff learning and satisfaction4–7 and found mixed results. None of these measured crashes. The issue of drowsy driving among house staff continues to remain in our collective blind spot, despite the fact that more than 1 decade ago, Barger et al.8 quantified postshift crash risk among interns. Crashes were most likely during the commute home after overnight shifts. Each monthly overnight shift adds to the risk of any crash by 9.1%, and to the risk of a crash during the commute from work by 16.2%. Are we ignoring the Institute of Medicine’s recommendation to address not only patient safety, but also the safety of our house staff?
A host of research methodologies are available to us to study the issue of drowsy driving in house staff. Experimental studies on test tracks or simulators, like the one by Huffmyer et al.,1 provide a safe alternative to on-road studies when evaluating driving impairment due to drowsiness. Translation of such experimental findings to real-world behavior and crash risk requires further validation, as was done recently.9 Complementary methods include review of crash databases and observational studies (human observer or in-vehicle monitoring).
As we employ these approaches, we must keep our focus on effective solutions beyond simply limiting the numbers of consecutive night shifts, which have shown mixed results on patient safety and house staff satisfaction and learning, and which may continue to leave house staff and others on the road vulnerable to drowsy driving-related vehicle accidents.
In the interim, evidence-based strategies to promote safe driving in all individuals are available from the National Sleep Foundation,10 the American Academy of Sleep Medicine,11 and the National Highway Traffic Safety Administration.12 Many of these guidelines are applicable to reducing drowsy driving among house staff. Some actionable next steps are listed below:
Create a culture change. Educate attending physicians and other leaders to promote and model good sleep hygiene; house staff to use strategic naps on duty and prioritize sleep during time off; and nursing staff to withhold nonurgent pages until daytime.
Conduct research to determine optimal shift lengths; shorter shifts could increase risk by requiring more postshift commutes overall, whereas longer shifts could increase risk through more prolonged sleep deprivation.
Invest in fatigue risk management programs for employees, including house staff.
a. Include sleepiness as part of safety and employee assistance strategies that address other forms of impairment.
b. Reimburse expenses for taxis and alternative modes of transportation.
c. Educate at-risk employees regarding signs of drowsy driving and effective countermeasures:
i. Signs: frequent yawning; difficulty keeping eyes open; head nodding or dropping; inability to remember driving the last few miles; missing road signs or turns; difficulty maintaining speed or lane position.
ii. Countermeasures:
At least two nights of extended sleep are required after a night of missed sleep; encourage “catch-up sleep” during off-duty periods.
If feeling drowsy, take a 15- to 30-min nap before driving home or find another means of travel.
Use caffeine judiciously, so that it does not interfere with sleep during time off.
For longer drives, naps may not be sufficient. Get plenty of sleep before traveling, or find alternative means of travel.
Do not rely on ineffective strategies, such as turning up the radio, opening the window, and turning up the air conditioner.
Measurement and testing:
a. Extend systems for monitoring safety and quality to include motor vehicle citation and crash outcomes among staff, particularly house staff.
b. When crashes occur after shifts, conduct detailed investigations to identify work-related, modifiable factors that could have contributed to crash causation.
c. Institute performance-based versus time-based methods to screen for excessive drowsiness.
As Huffmyer et al.1 show, solutions such as limiting consecutive night shifts to six are simplistic, and they leave house staff vulnerable to effects of sleep deprivation, which may increase their propensity for drowsy-driving-related vehicle crashes. Elegant, simulated driving evaluations, such as the ones they use, are promising tools that could identify drivers who are most vulnerable to the risks of drowsy driving. Such information is critical in developing a more personalized approach to reducing drowsy-driving crashes. House staff safety should no longer remain in our collective blind spot, but should receive the full attention it deserves.
Competing Interests
The authors are not supported by, nor maintain any financial interest in, any commercial activity that may be associated with the topic of this article.
