Occupational Safety & Sleep

Volpp, K.G., Shea, J.A., Small, D.S., Basner, M., Zhu, J., Norton, L., Ecker, A., Novak, C., Bellini, L.M., Dine, C.J., Mollicone, D.J., Dinges, D.F.: Effect of a protected sleep period on hours slept during extended overnight in-hospital duty hours among medical interns: A randomized trial. Journal of the American Medical Association 308(21): 2208-2217, 2012.

• Context: A 2009 Institute of Medicine report recommended protected sleep periods for medicine trainees on extended overnight shifts, a position reinforced by new AccreditationCouncil for Graduate Medical Education requirements.
• Objective: To evaluate the feasibility and consequences of protected sleep periods during extended duty.
• Design, Setting, and Participants: Randomized controlled trial conducted at the Philadelphia VA Medical Center medical service and Oncology Unit of the Hospital of the University of Pennsylvania (2009-2010). Of the 106 interns and senior medical students who consented, 3 were not scheduled on any study rotations. Among the others, 44 worked at the VA center, 16 at the university hospital, and 43 at both.
• Intervention: Twelve 4-week blocks were randomly assigned to either a standard intern schedule (extended duty overnight shifts of up to 30 hours; equivalent to 1200 overnight intern shifts at each site), or a protected sleep period (protected time from 12:30 AM to 5:30 AM with handover of work cell phone; equivalent to 1200 overnight intern shifts at each site). Participants were asked to wear wrist actigraphs and complete sleep diaries.
• Main Outcome Measures: Primary outcomewas hours slept during the protected period on extended duty overnight shifts. Secondary outcome measures included hours slept during a 24-hour period (noon to noon) by day of call cycle and Karolinska sleepiness scale.
• Results: For 98.3% of on-call nights, cell phones were signed out as designed. At the VA center, participants with protected sleep had amean 2.86 hours (95% CI, 2.57- 3.10 hours) of sleep vs 1.98 hours (95% CI, 1.68-2.28 hours) among those who did not have protected hours of sleep (P.001). At the university hospital, participants with protected sleep had a mean 3.04 hours (95% CI, 2.77-3.45 hours) of sleep vs 2.04 hours (95% CI, 1.79-2.24) among those who did not have protected sleep (P.001). Participants with protected sleep were significantly less likely to have call nights with no sleep: 5.8% (95% CI, 3.0%-8.5%) vs 18.6% (95% CI, 13.9%- 23.2%) at the VA center (P.001) and 5.9% (95% CI, 3.1%-8.7%) vs 14.2% (95% CI, 9.9%-18.4%) at the university hospital (P=.001). Participants felt less sleepy after on-call nights in the intervention group, with Karolinska sleepiness scale scores of 6.65 (95% CI, 6.35-6.97) vs 7.10 (95% CI, 6.85-7.33; P=.01) at the VA center and 5.91 (95% CI, 5.64-6.16) vs 6.79 (95% CI, 6.57-7.04; P.001) at the university hospital.
• Conclusions: For internal medicine services at 2 hospitals, implementation of a protected sleep period while on call resulted in an increase in overnight sleep duration and improved alertness the next morning.

Bakhru, R.N., Basner, M., Kerlin, M.P., Halpern, S.D., Hansen-Flaschen, J., Rosen, I.M., Dinges, D.F., Schweickert, W.D.: Sleep and work in ICU physicians during a randomized trial of nighttime intensivist staffing. Critical Care Medicine, 47(7), 894-902, 2019.

• Objectives: To compare sleep, work hours, and behavioral alertness in faculty and fellows during a randomized trial of nighttime in-hospital intensivist staffing compared to a standard daytime intensivist model
• Design: Prospective observational study.
• Setting: Medical Intensive Care Unit (MICU) of a tertiary care academic medical center during a randomized controlled trial of in-hospital nighttime intensivist staffing.
• Patients: 20 faculty and 13 fellows assigned to rotations in the MICU during 2012
• Interventions: As part of the parent study, there was weekly randomization of staffing model, stratified by 2-week faculty rotation. During the standard staffing model, there were in-hospital residents, with a fellow and faculty member available at nighttime by phone. In the intervention, there were in-hospital residents with an in-hospital nighttime intensivist. Fellows and faculty completed diaries detailing their sleep, work, and well-being; wore actigraphs; and performed psychomotor vigilance testing daily.
• Measurements and Main Results: Daily sleep time (mean hours (standard deviation)) was increased for fellows and faculty in the intervention vs control—6.7 (0.3) vs 6.0 (0.2), p<0.001 and 6.7 (0.1) vs 6.4 (0.2), p<0.001, respectively. In-hospital work duration did not differ between the models for fellows or faculty. Total hours of work done at home was different for both fellows and faculty—0.1 (<0.1) intervention vs 1.0 (0.1) control, p<0.001 and 0.2 (<0.1) intervention vs 0.6 (0.1) control, p<0.001, respectively. Psychomotor vigilance testing did not demonstrate any differences. Measures of well-being including physical exhaustion and alertness were improved in faculty and fellows in the intervention staffing model.
• Conclusions: Although no differences were measured in patient outcomes between the two staffing models, in-hospital nighttime intensivist staffing was associated with small increases in total sleep duration for faculty and fellows, reductions in total work hours for fellows only, and improvements in subjective well-being for both groups. Staffing models should consider how work duration, sleep, and well-being may impact burnout and sustainability.

Shea, J.A., Dinges, D.F., Small, D.S., Basner, M., Zhu, J., Norton, L., Ecker, A.J., Novak, C., Bellini, L.M., Dine, C.J., Mollicone, D.J., Volpp, K.G.: A randomized trial of a 3-hour protected nap period in a medicine training program: Sleep, alertness and patient outcomes. Academic Medicine 6: 256-263, 2014

• Purpose: Protected sleep periods for internal medicine interns have previously resulted in increased amount slept and improved cognitive alertness but required supplemental personnel. The authors evaluated intern and patient outcomes associated with protected nocturnal nap periods of three hours that are personnel neutral.
• Method: Randomized trial at Philadelphia Veterans Affairs Medical Center (PVAMC) Medical Service and Hospital of the University of Pennsylvania (HUP) Oncology Unit. During 2010–2011, four-week blocks were randomly assigned to a standard intern schedule (extended duty overnight shifts of up to 30 hours), or sequential protected sleep periods (phone sign-out midnight to 3:00 am [early shift] intern 1; 3:00 to 6:00 am [late shift] intern 2). Participants wore wrist Actiwatches, completed sleep diaries, and performed daily assessments of behavioral alertness. Between-group comparisons of means and proportions controlled for withinperson correlations.
• Results: HUP interns had significantly longer sleep durations during both early (2.40 hours) and late (2.44 hours) protected periods compared with controls (1.55 hours, P < .0001). At PVAMC sleep duration was longer only for the late shift group (2.40 versus 1.90 hours, P < .036). Interns assigned to eitherprotected period were significantly less likely to have call nights with no sleep and had fewer attentional lapses on the Psychomotor Vigilance Test. Differences in patient outcomes between standard schedule months versus intervention months were not observed.
• Conclusions: Protected sleep periods of three hours resulted in more sleep during call and reductions in periods of prolonged wakefulness, providing a plausible alternative to 16-hour shifts.

Basner, M., Dinges, D.F., Shea, J.A., Small, D.S., Zhu, J., Norton, L., Ecker, A.J., Novak, C., Bellini, L.M., Volpp, K.G.: Sleep and alertness in medical interns and residents: an observational study on the role of extended shifts. Sleep 40(4): zsx027, 1-8, 2017.

• Study Objectives: Fatigue from sleep loss is a risk to physician and patient safety, but objective data on physician sleep and alertness on different duty hour schedules is scarce. This study objectively quantified differences in sleep duration and alertness between medical interns working extended overnight shifts and residents not or rarely working extended overnight shifts.
• Methods: Sleep–wake activity of 137 interns and 87 PGY-2/3 residents on 2-week Internal Medicine and Oncology rotations was assessed with wristactigraphy. Alertness was assessed daily with a brief Psychomotor Vigilance Test (PVT) and the Karolinska Sleepiness Scale.
• Results: Interns averaged 6.93 hours (95% confidence interval [CI] 6.84–7.03 hours) sleep per 24 hours across shifts, significantly less than residents not working overnight shifts (7.18 hours, 95% CI 7.06–7.30 hours, p = .007). Interns obtained on average 2.19 hours (95% CI 2.02–2.36 hours) sleep during on-call nights (17.5% obtained no sleep). Alertness was significantly lower on mornings after on-call nights compared to regular shifts (p < .001). Naps between 9 am and 6 pm on the first day post‐call were frequent (90.8%) and averaged 2.84 hours (95% CI 2.69–3.00 hours), but interns still slept 1.66 hours less per 24 hours (95% CI 1.56–1.76 hours) compared to regular shift days (p < .001). Sleep inertia significantly affected alertness in the 60 minutes after waking on-call.
• Conclusions: Extended overnight shifts increase the likelihood of chronic sleep restriction in interns. Reduced levels of alertness after on-call nights need to be mitigated. A systematic comparison of sleep, alertness, and safety outcomes under current and past duty hour rules is encouraged.

Shea, J.A., Bellini, L.M., Dinges, D.F., Curtis, M.L., Tao, Y., Zhu, J., Small, D.S., Basner, M., Norton, L., Novak, C., Dine, C., Rosen, I.M., Volpp, K.G.: The impact of protected sleep period for internal medicine interns on overnight call on depression, burnout, and empathy. Journal of Graduate Medical Education 6(2): 256-263, 2014.

• Background: Patient safety and sleep experts advocate a protected sleep period for residents.
• Objective: We examined whether interns scheduled for a protected sleep period during overnight call would have better end-of-rotation assessments of burnout, depression, and empathy scores compared with interns without protected sleep periods and whether the amount of sleep obtained during on call predicted end-of-rotation assessments.
• Methods: We conducted a randomized, controlled trial with internal medicine interns at the Philadelphia Veterans Affairs Medical Center (PVAMC) and the Hospital of the University of Pennsylvania (HUP) in academic year 2009– 2010. Four-week blocks were randomly assigned to either overnight call permitted under the 2003 duty hour standards or a protected sleep period from 12:30 AM to 5:30 AM. Participants wore wrist actigraphs. At the beginning and end of the rotations, they completed the Beck Depression Inventory (BDI-II), Maslach Burnout Inventory (MBI-HSS), and Interpersonal Reactivity Index (IRI).
• Results: A total of 106 interns participated. There were no significant differences between groups in end-of-rotation BDI-II, MBI-HSS, or IRI scores at either location (P ..05). Amount of sleep while on call significantly predicted lower MBI-Emotional Exhaustion (P ,.003), MBIDepersonalization (P ,.003), and IRI-Personal Distress (P ,.006) at PVAMC, and higher IRI-Perspective Taking (P ,.008) at HUP.
• Conclusions: A protected sleep period produced few consistent improvements in depression, burnout, or empathy, although depression was already low at baseline. Possibly the amount of protected time was too small to affect these emotional states or sleep may not be directly related to these scores.

Rogers AE, Hwang W-T, Scott LD, Aiken LH, Dinges DF. The working hours of hospital staff nurses and patient safety.  Health Affairs 23(4):  202-212, 2004.  PMID:  15318582

• ABSTRACT: The use of extended work shifts and overtime has escalated as hospitals cope with a shortage of registered nurses (RNs). Little is known, however, about the prevalence of these extended work periods and their effects on patient safety. Logbooks completed by 393 hospital staff nurses revealed that participants usually worked longer than scheduled and that approximately 40 percent of the 5,317 work shifts they logged exceeded twelve hours. The risks of making an error were significantly increased when work shifts were longer than twelve hours, when nurses worked overtime, or when they worked more than forty hours per week

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.

• Study Design: 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.
• Key Findings: The researchers identified optimal decision thresholds of 11 and 20 lapses on the 3-minute PVT that successfully divided threat detection performance into high, medium, and low performance groups. These performance categories replicated expected homeostatic and circadian patterns during sleep deprivation, with threat detection accuracy decreasing significantly across the three groups.
• 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).
• Practical Applications: The findings suggest three performance categories for operational use:
• High performance: 0-11 lapses (fit for duty)
• Medium performance: 12-20 lapses (may continue with warning)
• Low performance: >20 lapses (should not perform task)
• Limitations: The study used non-professional volunteers rather than trained screeners, employed a higher threat prevalence than typical airport operations, and was conducted in a laboratory rather than operational environment.
• Conclusion: The 3-minute PVT successfully predicted performance on simulated luggage screening tasks and should be validated further with professional screeners in operational environments.

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.

• This study investigated how night work and sleep loss affect threat detection in simulated airport luggage screening.
• Study Design: 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.
• Key Findings:
• Both night work and sleep loss significantly impaired threat detection performance. During night work, detection accuracy dropped from 0.808 to 0.785, while false alarms increased. After sleep deprivation, hit rates fell from 57.3% to 53.8%. Performance remained stable for the first 16 hours of wakefulness but deteriorated rapidly afterward, with worst performance at 7:00 AM after 23 hours awake.
• 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).
• Practical Significance: 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.
• Limitations: The study used non-professional volunteers rather than trained screeners, employed higher threat prevalence than typical operations, and was conducted in a laboratory setting.
• Conclusion: This provided the first systematic evidence that fatigue from night work and sleep loss impairs visual threat detection accuracy, suggesting airport security operations may need fatigue countermeasures to maintain safety.

Basner, M., Asch, D.A., Shea, J.A., Bellini, L.M., Carlin, M., Ecker, A.J., Malone, S.K., Desai, S.V., Sternberg, A.L., Tonascia, J., Shade, D.M., Katz, J.T., Bates, D.W., Even-Shoshan, O., Silber, J.H., Small, D.S., Volpp, K.G., Mott, C.G., Coats, S., Mollicone, D.J., Dinges, D.F., on behalf of the iCOMPARE Research Group: Sleep and alertness in a duty-hour flexibility trial in Internal Medicine. New England Journal of Medicine, 380(10), 915-924, 2019.

• Silber, J.H., Bellini, L.M., Shea, J.A., Desai, S.V., Dinges, D.F., Basner, M., Even-Shoshan, O., Hill, A.S., Hochmann, L.L., Katz, J.T., Ross, R.N., Shade, D.M., Small, D.S., Sternberg, A.L., Tonascia, J., Volpp, K.G., Asch, D.A., for the iCOMPARE Research Group: Patient safety outcomes under flexible and standard resident duty-hour rules. New England Journal of Medicine, 380(10), 905-914, 2019

• Cordoza, M.*, Basner, M.*, Asch, D.A., Shea, J.A., Bellini, L.M., Carlin, M., Ecker, A.J., Malone, S.K., Desai, S.V., Katz, J.T., Bates, D.W., Small, D.S., Volpp, K.G., Mott, C.G., Coats, S., Mollicone, D.J., Dinges, D.F., iCOMPARE Research Group: Sleep and alertness among interns in intensive care compared to general medicine rotations: a secondary analysis of the iCOMPARE trial. Journal of Graduate Medical Education, 13(5): 717–721, 2021. *co-first authors

• Zhang, J., Basner, M., Jones, C.W., Dinges, D.F., Shou, H., Li, H.: Mediation analysis with random distribution as mediator with an application to iCOMPARE trial. Statistics in Biosciences, 16: 107–128, 2024.

• Desai, S.V., Asch, D.S., Bellini, L.M., Chaiyachati, K.H., Liu, M., Sternberg, A.L., Tonascia, J., Yeager, A.M., Asch, J.M., Katz, J.T., Basner, M., Bates, D.W., Bilimoria, K.Y., Dinges, D.F., Even-Shoshan, O., Shade, D.M., Silber, J.H., Small, D.S., Volpp, K.G., Shea, J.A., and the iCOMPARE Research Group: Education outcomes from a duty-hour flexibility trial in Internal Medicine. New England Journal of Medicine, 378(16): 1494-1508, 2018.

• Shea, J.A., Basner, M., Bates, D.W., Bellini, L.M., Chaiyachati, K.H., Desai, S.V., Dinges, D.F., Even-Shoshan, O., Katz, J.T., Shade, D.M., Silber, J.H., Small, D.S., Sternberg, A.L., Tonascia, J., Volpp, K.G., Asch, D.A.: Development of the individualized Comparative Effectiveness of Models Optimizing Patient Safety and Resident Education (iCOMPARE) Trial: A national cluster-randomized trial of resident duty hour policies in Internal Medicine. BMJ Open, 8:e021711: 1-11, 2018.

• Gurubhagavatula, I., Barger, L., Barnes, C.M., Basner, M., Boivin, D.B., Dawson, D., Drake, C.L., Flynn-Evans, E.E., Mysliwiec, V., Patterson, P.D., Reid, K.J., Samuels, C., Lewis Shattuck, N., Kazmi, U., Carandang, G., Heald, J.L., Van Dongen, H.P.A.: Guiding principles for determining work shift duration and addressing the effects of work shift duration on performance, safety, and health. Journal of Clinical Sleep Medicine, 17(11): 2283-2306, 2021.

• Balkin TJ, Horrey WJ, Graeber RC, Czeisler CA, Dinges DF.  The challenges and opportunities of technological approaches to fatigue management. Accident Analysis and Prevention 43(2):565-72, Mar 2011.  PMID:  21130217

Van Dongen HPA, Maislin G, Dinges DF. Dealing with inter-individual differences in the temporal dynamics of fatigue and performance: Importance and techniques. Aviation, Space & Environmental Medicine 75 (3):A147-A154, 2004.  PMID:  15018277

• 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.

• 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.

• 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

• 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.  PMID:  12137101

• 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.  PMID:  12190073

• 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.  PMID:  16690976/PMCID:  PMC2648121

• 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.

• 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.

• 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.

• 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.