Occupational Safety & Sleep: Pilots, truck drivers and transit agencies

Read more here: Elmenhorst, E.-M., Vejvoda, M., Maaß, H., Wenzel, J., Plath, G., Schubert, E., Basner, M.: Pilot workload during approaches: Comparison of simulated standard and noise-abatement profiles. Aviation, Space, and Environmental Medicine 80(4), 364-370, 2009.

This research examined pilot workload when performing a new noise-reduction landing approach called the Segmented Continuous Descent Approach (SCDA) compared to the standard procedure. The study measured workload in 40 pilots using heart rate, blood pressure, blink frequency, saliva cortisol, and self-reported measures of fatigue, sleepiness, tension, and task load. The approaches were conducted in A320 and A330 full-flight simulators during night shifts, with Segmented Continuous Descent Approach (SCDA) compared against the reference Low Drag Low Power (LDLP) procedure. Both approach procedures caused a similar workload level. While this study was limited in using flight simulators, it can be concluded that under these ideal conditions, the SCDA is operable without a higher workload for pilots compared to the common LDLP.

Read more here: Vejvoda, M., Elmenhorst, E.-M., Pennig, S., Plath, G., Maaß, H., Tritschler, K., Basner, M., Aeschbach, D.: Significance of time awake for predicting pilots' fatigue on short-haul flights: implications for flight duty time regulations. Journal of Sleep Research 23(5): 564-7, 2014.

Read more here: Neri DF, Oyung RL, Colletti LM, Mallis MM, Tam PY, Dinges DF. Controlled breaks as a fatigue countermeasure on the flight deck. Aviation Space & Environmental Medicine 73 (7):654-664, 2002.

This NASA-funded research conducted by the Fatigue Countermeasures Group investigated whether short, controlled breaks could effectively reduce pilot fatigue during long, automated nighttime flights. While surveys revealed many pilots use breaks as an in-flight countermeasure, there had been no controlled studies of their effectiveness. A 6-hour, uneventful, nighttime flight in a Boeing 747-400 flight simulator was flown by fourteen two-man crews. The 14 subjects in the treatment group received 5 short breaks spaced hourly during cruise; the 14 subjects in the control group received 1 break in the middle of cruise. Continuous EEG/EOG, subjective sleepiness, and psychomotor vigilance performance data were collected. The physiological and subjective data indicate the breaks reduced nighttime sleepiness for at least 15 min post-break and may have masked sleepiness for up to 25 min, suggesting the potential usefulness of short-duration breaks as an in-flight fatigue countermeasure.

Read more here: Kelly SM, Rosekind MR, Dinges DF, Miller DL, Gillen KA, Gregory KB, Aguilar RD, Smith RM. Flight controller alertness and performance during spaceflight shiftwork operations. Human Performance in Extreme Environments 3 (1):100-106, 1998.

Decreased alertness and performance associated with fatigue, sleep loss, and circadian disruption are issues faced by a diverse range of shiftwork operations personnel. During Space Transportation System (STS) operations, Mission Operations Directorate (MOD) personnel provide 24-hr. coverage of critical tasks. A joint NASA Johnson Space Center and NASA Ames Research Center project was undertaken to examine these issues in flight controllers during MOD shiftwork operations. An initial operational test of procedures and measures was conducted during the STS-53 mission in December 1992. The initial results clearly support the need for further data collection during other STS missions to document baseline levels of alertness and performance during MOD shiftwork operations. Implementation and evaluation of the countermeasure strategies to maximize alertness and performance is planned. As STS missions extend to further EDO (extended duration orbiters), and timelines and planning for 24-hour Space Station operations continue, alertness and performance issues related to sleep and circadian disruption will remain highly relevant in the MOD environment.

Read more here: Basner, M., Rubinstein, J.: Fitness for duty: A 3 minute version of the Psychomotor Vigilance Test predicts fatigue related declines in luggage screening performance. Journal of Occupational and Environmental Medicine 53(10): 1146-1154, 2011.

Thirty-six healthy volunteers (average age 30.8 years) participated in a laboratory study involving 34 hours of total sleep deprivation, with testing every 2 hours. The study found strong correlation between PVT performance and luggage screening ability. High performers detected threats at a rate 7% higher than low performers. The classification system proved both sensitive (detecting impaired individuals after extended wakefulness) and specific (correctly identifying most people as capable during normal daytime hours).

Read more here: Basner, M., Rubinstein, J., Fomberstein, K.M., Coble, M.C., Ecker, A., Avinash, D., Dinges, D.F.: Effects of night work, sleep loss and time on task on simulated threat detection performance. Sleep 31(9), 1251-1259, 2008.

With 700 million bags screened annually at U.S. airports, even modest performance decrements could result in substantial numbers of missed threats and unnecessary security delays. In this study, twenty-four healthy volunteers participated in a 5-day laboratory study with 35 hours of continuous wakefulness. They screened over 5,800 simulated X-ray images of luggage every 2 hours, with 25% containing guns or knives, in order to investigate how night work and sleep loss affect threat detection in simulated airport luggage screening. 

Within each screening session, hit rates declined from 60.2% to 52.2%, demonstrating the classic "vigilance decrement" that was most pronounced in the first minutes. Subjects became increasingly conservative in their judgments as fatigue set in. Guns were detected more easily than knives, and simpler threats were spotted more readily than complex ones (detection rates ranged from 75.3% for easy guns to 32.5% for difficult knives).

Read more here: Dinges, D.F., Maislin, G.: Truck Driver Fatigue Management Survey. Final report to the Federal Motor Carrier Safety Administration, U.S. Department of Transportation, pp. 1-82, November 23, 2005.

This project identified factors related to causes of fatigue and ways to manage fatigue in commercial drivers working for the Motor Freight Carrier Association. The goal of the project was to identify best practices for managing fatigue that may be applicable to other motor vehicle operators. A survey instrument was developed and used to investigate the experiences and practices of more than 2,000 Teamster LTL drivers, some of whom had driven a million or more miles accident free. Responses from 1,128 million miler drivers were compared to those of 1,152 non-million miler drivers.

Read more here: Grace R, Guzman A, Staszewski J, Dinges DF, Mallis M, Peters BA. The Carnegie Mellon truck simulator, a tool to improve driving safety. Society of Automotive Engineers International: Truck and Bus Safety Issues SP1400:1-6, 1998.

The Advanced Human Factors Research and Driving Training Research Facility was designed to validate the usefulness of simulators for driver training and to inform countermeasures for driver fatigue and driver/vehicle interface issues. 

Read more here: Pack AI, Maislin G, Staley B, Pack FM, Rogers W, George CFP, Dinges DF. Impaired performance in commercial drivers:  Role of sleep apnea and sleep duration. American Journal of Respiratory and Critical Care Medicine, 174:446-454, 2006.

Studies were conducted in 247 of 551 drivers at higher risk for apnea and in 159 of 778 drivers at lower risk. Increases in subjective sleepiness were associated with shorter sleep durations but not with increases in severity of apnea. Increases in objective sleepiness and performance lapses, as well as poorer lane tracking, were associated with shorter sleep durations.

Read more here: Mallis, M., Maislin, G., Konowal, N., Byrne, V., Bierman, D., Davis, R., Grace, R., Dinges, D.F.: Biobehavioral responses to drowsy driving alarms and alerting stimuli. Final report to develop, test and evaluate a drowsy driver detection and warning system for commercial motor vehicle drivers sponsored by the National Highway Traffic Safety Administration, Federal Highway Administration, Office of Motor Carriers, 2000.

16 CDL holders drove a high-fidelity truck simulator to establish the effects of informational feedback about drowsiness
while driving on driver alertness-drowsiness, driving performance, and driver-initiated behaviors. The drowsiness feedback system tested was developed at Carnegie Mellon Research Institute (CMRI) and was comprised of an infrared, retinal reflectance PERCLOS monitor
that provided minute-to-minute feedback to drivers regarding their alertness-drowsiness, which could trigger alarms if drowsiness was sustained or reached high levels. 

Read more here: Dinges DF, Maislin G, Brewster RM, Krueger GP, Carroll RJ: Pilot test of fatigue management technologies. Transportation Research Record: Journal of the Transportation Research Board No. 1922, Transportation Research Board of the National Academies, Washington, DC, 175-182, 2005.

This study involved over-the-road testing of four fatigue management technologies (FMTs) in trucking operations in Canada and the United States. The objective was to determine driver reactions to such technologies and whether FMT feedback would improve alertness, especially during night driving, or increase sleep time on workdays or non-workdays. During night driving, FMT feedback significantly reduced driver drowsiness and lane tracking variability. However, there was evidence from probed psychomotor vigilance task testing that these improvements may have had cost because of the effort (in attention and compensatory behaviors) required to respond to information from the devices. In general, participants agreed that commercial drivers would benefit from FMT and were more positive about those involving vehicle monitoring than those involving driver monitoring.

Read more here: Dinges, D.F., Maislin, G., Hanowski, R.J., Mollicone, D.J., Hickman, J.S., Maislin, D., Kan, K., Hammond, R.L., Soccolich, S.A., Moeller, D.D., Trentalange, M. Commercial Motor Vehicle (CMV) Driver Restart Study: Final Report. U.S. DoT; Federal Motor Carrier Safety Administration; Office of Analysis, Research, and Technology. 188 pages, 2015.

The Federal Motor Carrier Safety Administration (FMCSA) funded this study on the operational, safety, health, and fatigue impacts of two 'restart' provisions for commercial motor vehicle (CMV) drivers, which would require two nighttime periods [1–5 a.m.] during a 34-hour restart, and the requirement for a minimum of 168 hours between the beginning of a 34-hour restart period and the beginning of the previous 34-hour restart period.