Fatigue & Driving: Risks and Preventive Strategies

1. Fatigue & Driving: Who is At RiskA Laboratory and Field Perspective Christopher L. Drake, PhDWake Up Michigan!September 20, 2007 Christopher Drake, PhD, D.ABSM Senior Bioscientific Staff Henry Ford Hospital Sleep Center Assistant Professor Wayne State University College of Medicine

2. The Sleep Facts • Adult sleep need is 8.2 per 24 hours, with little variability (homeostatic “set point”) • Impairment in performance occurs with as little as 2 hours less per night. • Sleep debt from restricting sleep to 5-6 hours a night accumulates with time, and awareness of sleepiness declines. • Circadian timing has a major impact on performance, and is not addressed in many service guidelines (i.e., truckers, aviation)

3. Behavioral/Mood Sleepiness Psychomotor Impairment Accidents Decreased Work Productivity Reduced Quality of Life Deficits in Learning/Memory Stimulant Seeking Alcohol Interaction Mood Effects Lack of Awareness Physiologic Hypoxemia Insulin Resistance Sympathetic Activity Blunted Arousal Response (hypoxemia, C02, EEG) Consequences of Sleep Loss

4. The Scope of the Problem • Estimates by US National Highway Traffic Safety Administration • 1-4% of highway crashes caused by sleepiness • Principal cause in 100,000 police-reported crashes • 4% of all fatal accidents caused by sleepiness • A drowsy driver operating a motor vehicle at 60 mph in the right-hand lane (12’ wide) of a divided highway with a breakdown lane (11’ wide) can drift off the road at ~4° angle in less than 4 seconds National Highway Traffic Safety Administration. 2002. Available at: http://www.nhtsa.dot.gov.

6. Causes of Excessive Daytime Sleepiness • Reduced Sleep at Night Reduced Sleep Length Reduced Sleep Continuity • Circadian Phase • CNS acting Drugs • CNS Diseases

7. Reported Total Sleep Time (Ages 18-23) Terman & Hocking, 1913 Roth, et al, 2003 (unpubl) Reported Total Sleep Time (hrs/night) Survey Year

8. Mean Reported Nightly Total Sleep Time (2-weeks) N=3283 6.8 hrs/nt 10% 15% 8% Percent 6% 4% 2% 180 240 300 360 420 480 540 600 660 Nightly Total Sleep Time (min) Drake et al., 2002

9. Sleepiness accumulates over time 4h TIB 6h TIB Experiments on chronic restriction of sleep from 1-2 weeks reveal cumulative increases in lapse rates in a sleep-dose response manner. 8h TIB 3h TIB • A. Van Dongen HPA et al. Sleep. 2003;26:117-126. • Belenky G et al. J. Sleep Res. 2003;12:1-12. • Review: Dinges DF et al. Chronic Sleep Restriction. In: Kryger MH et al. (Ed.) Principles and Practice of Sleep Medicine W.B. Saunders, Philadelphia, PA, 2005, 67-76. 5h TIB 7h TIB 9h TIB

11. International Data N = 6052 Vehicle Accident Data 1200 1100 1000 900 800 700 600 500 400 300 200 100 No. of Accidents Midnight Noon 6 PM Midnight 6 AM Mitler MM, et al. Sleep. 1988.

12. Midnight Noon 6 PM Midnight 6 AM Overlay of Vehicle Accident Data, Performance Errors, and Circadian Rhythms

13. Populations at High Risk Of Sleepiness/Fatigue Related Accidents

14. Relationship between sleepiness & Accidents • Approximately 27% of drivers who have lost consciousness behind the wheel fell asleep as opposed to fainting, seizure, heart attack, etc. • Importantly, this 27% accounted for 83% of the fatalities. Parsons, 1986 QJM.

15. Extended Work Shifts and Risk for Motor Vehicle Accidents Among Interns 0 Extended Shifts Nonextended Shifts (<24 h) 1-4 Extended Shifts Extended Shifts (≥24 h) >4 Extended Shifts * * 3.7 * 5.9 * * Odds Ratio (95% CI) 2.4 Odds Ratio (95% CI) * 1.7 1.8 2.3 1.0 1.0 1.0 1.0 Near-missIncidents Crashes Driving Stopped Nod Off or Fall Asleep *P <0.05 vs nonextended shifts or no extended shifts.Barger LK, et al. N Engl J Med. 2005;352:125-134.

16. Obstructive Sleep Apnea Courtesy of Dr. Jonathan R.L. Schwartz. University of Oklahoma Health Sciences Center.

18. Excessive Sleepiness and DrivingCollisions, Costs and Fatalities • Consequences of OSAS • 810K collisions • $15.9 billion in collision costs • 1,400 fatalities • Estimated cost-savings with CPAP treatment • Prevent >500K collisions • Reduce collision costs by $11.1 billion • Save nearly 1,000 lives Meta-Analysis of 6 studies: Risk of MVC is greater in drivers with OSAS than drivers without OSAS Findley, 1998 Barbe, 1998 Teran-Santos, 1999 Hortsmann, 2000 Lioberes, 2000 George, 2001 Fixed Combined 0.5 1 2 5 10 Odds Ratio CPAP, continuous positive airway pressure; MVC, motor-vehicle collision; OSAS, obstructive sleep apnea syndrome. Sassani A, et al. Sleep. 2004;27(3):453-458.

19. Car Crashes in Sleep Apnea Patients 0.6 0.5 0.4 Crashes/Driver/5-Year (Millions) 0.3 0.2 0.1 0 All Drivers(N=3.7) Mild Apnea(N=16) Moderate Apnea(N=17) Severe Apnea(N=13) Findley LJ et al. N Engl J Med 1989.

20. Epidemiology Established OSA=5% 95% of patients with clinically significant and treatable OSA remain undiagnosed

21. Hours of Sleep and Equivalent Blood Alcohol Level for Sedative Effects Legal Intoxication† BrEC, %* Sleep time (hours in bed) *Approximate breath ethanol concentration (BrEC) at peak; †Above 0.05% for legal intoxication in many states. N=32 healthy subjects without prior sleep deprivation and with 85% sleep efficiency. Sleep loss group (n=12) was tested in all 4 conditions, with 3 to 7 days of recovery time between tests, and compared with ethanol group (n=20). Roehrs T, et al. Sleep. 2003;26:981-985.

22. Combined Effects • Sleep deprivation is often combined with other impairment (e.g., alcohol) and these combined effects can be devastating to driver performance

23. Driving Simulator Data

24. Sleep-Alcohol Interaction(Driving Simulator—AM) 40 Placebo 35 Ethanol 30 25 Off-Road Deviations 20 15 10 5 0 8 HR 4 HR Time in Bed (Mean [SEM]) Roehrs, et al. Alcohol Clin Exp Res 1994;18:154.

25. Sleep Deprivation Is Associated With Decreased Cortical Activity 18FDG PET Study of Healthy, Sleep-Deprived Adults, Showing Decreased Metabolism in the Thalamus, Prefrontal Cortex, and Inferior Parietal Cortex Inferior parietal cortex Prefontal cortex Occipitalcortex Thalamus FDG, fluorodeoxyglucose; PET, positron emission tomography. Thomas M et al. JSleep Res. 2000;9:335.

26. Detection of “Microsleeps” in Medical Residents Physiologic State Sleep Wake Sleep 51% 12% Reported State Wake 49% 88% 100% 100% Howard et al., 2002

27. Subjective vs. Objective Sleepiness During 4 nights of “Gradual” Sleep Loss (6hrs TIB) Subjective “Fatigue” MSLT (min) Drake et al., 2001

29. Time in Bed and Excessive Sleepiness 18 16 14 12 R2=0.9791 10 MSLT Latency (Minutes) 8 6 4 2 0 0 6 4 8 Time in Bed (Hours) * standard deviation; MSLT = Multiple Sleep Latency Test; Rosenthal L et al. (1993), Sleep 16(3):226-232

30. Crashes and the MSLT (10 year prevalence) N=69 N=204 Crash % N=345 SEVERE MODERATE ALERT Multiple Sleep Latency Test Groups Drake et al., prelim. data Cochran-Armitage Trend Test, p = .048

31. * Severe Injury Accidents Only * N=69 % subjects with crash N=345 N=204 < 5 5-10 >10 SEVERE MODERATE ALERT Multiple Sleep Latency Test Groups * p < .05; Cochran-Armitage, p = .028 Severe injury accidents were those which “prevent normal activities and require hospitalization”

32. 100-Car Study: Crashes and Near-crashes

33. 100-Car Study • Drowsiness also appears to affect crashes and collisions at much higher rates than is reported using existing crash databases. Drowsiness was a contributing factor in 12 percent of all crashes and 10 percent of near-crashes, while most current database estimates place drowsiness-related crashes at approximately 2 to 4 percent of total crashes.

34. Summary • Sleep need is ~8 hours per 24 • Sleepiness can be measured physiologically • Reduced sleep below 6 hrs/nt = Excessive sleepiness • Detection of sleepiness/fatigue and judgment is impaired with chronic sleep loss • Many segments of the population are at increased risk • The extent of sleep-related accidents is probably underestimated • Countermeasures = “sleep” not “rest”