Harvard Work Hours Health and Safety Group

Division of Sleep and Circadian Disorders, Brigham and Women's Hospital
Director: Charles A. Czeisler, PhD, MD, FRCP



Founded in 2001, the Harvard Work Hours Health and Safety Group (HWHHSG), is a multi-disciplinary collaborative whose mission is to improve the health and safety of those in safety-sensitive occupations.  The HWHHSG’s research focuses on work hours, sleep deficiency, circadian disruption and sleep disorders and the association of these factors with physical and mental health and safety outcomes, such as motor vehicle crashes and occupational injuries.

The HWHHSG has studied the work hours, health and safety of numerous occupational groups including police officers, firefighters, federal air marshals, maritime bar pilots, truck drivers, astronauts, and flight mission controllers. HWHHSG research has a wide reach, having conducted large-scale surveys of approximately 5,000 police officers in North America, nearly 7,000 firefighters in 66 fire departments across the country and more than 15,000 resident physicians in the United States.  Funding for HWHHSG research has been provided by the National Institute for Occupational Safety and Health, the Centers for Disease Control and Prevention, the National Institute of Justice, Agency for Healthcare Research and Quality and the Federal Emergency Management Agency.

Another critical element of the HWHHSG’s mission is to translate laboratory-tested countermeasures into operational environments and ensure their feasibility, acceptability and effectiveness in “real world” situations.  The HWHHSG team also  provides sleep health education to organizations, alone or as part of a comprehensive fatigue risk management program.  The educational component and outreach of HWHHSG research is operated under the Sleep Matters Initiative. The educational programs are availabe in multiple platforms including in-person, train-the trainer, and web-based. See https://www.railroadersleep.org/ for an example of internet-based educational program developed by the Harvard Medical School Division of Sleep Medicine, HWHHSG and the SMI.

Affiliated Faculty
  • Salim Qadri, BS
  • Jason P. Sullivan, BS
  • Natalie C. Viyaran, BS
  1. Blackwell T, Kriesel DR, Vittinghoff E, O'Brien CS, Sullivan JP, Viyaran NC, Rahman SA, Lockley SW, Barger LK, Halbower AC, Poynter SE, Wright KP Jr, Yu PL, Zee PC, Landrigan CP, Czeisler CA, Stone KL; ROSTERS Study Group. Design and recruitment of the randomized order safety trial evaluating resident-physician schedules (ROSTERS) study. Contemp Clin Trials. 2019 May;80:22-33.
  2. Barger,LK, Sullivan, JP, Blackwell, T, O’Brien, CS, St. Hillaire, MA, Rahman, S, Phillips, AJK, Qadri, S, Wright, KP, Segar, JL, McGuire, JK, Vitiello, MV, de la Iglesia, HO, Poynter, SE, Yu, PL, Zee, P, Sanderson, AL, Halbower, AC, Lockley, SW, Landrigan, CP, Stone, KL, Czeisler on behalf of the ROSTERS Study Group. Effects on Resident Work Hours, Sleep Duration and Work Experience in a Randomized Order Safety Trial Evaluating Resident-physician Schedules (ROSTERS). Sleep. 2019. https://doi.org/10.1093/sleep/zsz110.
  3. Wolkow, AP, Barger, LK, O’Brien, CS, Sullivan, JP, Qadri, A, Lockley, SW, Czeisler, CA, Rajaratnam, SMW. Associations between sleep disturbances, mental health outcomes and burnout in firefighters, and the mediating role of sleep during overnight work: A cross-sectional study. Journal of Sleep Research. 2019:e12869. https://doi.org/10.1111/jsr.12869 [published Online First: 2019/05/28].
  4. Weaver MD, Landrigan CP, Sullivan JP, et al. The Association Between Resident Physician Work-Hour Regulations and Physician Safety and Health [published online ahead of print, 2020 Feb 13]. Am J Med. 2020;S0002-9343(20)30116-9. doi:10.1016/j.amjmed.2019.12.053
  5. Landrigan, CP, Rahman, SA, Sullivan, JP, Vittinghoff, E, Barger, LK, Sanderson, AL, Wright, KP, O’Brien, CS, Qadri, S, St.Hillaire, MA, Halbower, AC, Segar, JL, McGuire, JK, Vitiello, MV, de la Iglesia, HO, Poynter, SE, Yu, PL, Zee, PC, Lockley, SW, Stone, KL, Czeisler, CA, for the ROSTERS Study Group. Effect on Patient Safety of a Resident-Physician Schedule without > 24 hour Shifts. NEJM. In Press.
  6. Landrigan CP, Rothschild JM, Cronin JW, Kaushal R, Burdick E, Katz JT, Lilly CM, Stone PH, Lockley SW, Bates DW, Czeisler CA. Effect of reducing interns' work hours on serious medical errors in intensive care units. N Engl J Med. 2004 Oct 28;351(18):1838-48.
  7. Lockley SW, Cronin JW, Evans EE, Cade BE, Lee CJ, Landrigan CP, Rothschild JM, Katz JT, Lilly CM, Stone PH, Aeschbach D, Czeisler CA; Harvard Work Hours, Health and Safety Group. Effect of reducing interns' weekly work hours on sleep and attentional failures. N Engl J Med. 2004 Oct 28;351(18):1829-37.
  8. Barger LK, Cade BE, Ayas NT, Cronin JW, Rosner B, Speizer FE, Czeisler CA; Harvard Work Hours, Health, and Safety Group. Extended work shifts and the risk of motor vehicle crashes among interns. N Engl J Med 2005; 352(2):125-34.
  9. Landrigan CP, Lockley SW, Czeisler CA. Effect of intern's consecutive work hours on safety, medical education and professionalism. Crit Care. 2005 Oct 5;9(5):528-30; author reply 528-30. Epub 2005 May 24. 
  10. Landrigan CP, Barger LK, Cade BE, Ayas NT, Czeisler, CA. Interns’ Compliance with Accreditation Council for Graduate Medical Education Work-Hour Limits. JAMA 2006; 296(9):1063-1070.
  11. Ayas, NT, Barger, LK, Cade BE, Hashimoto, D, Rosner, B, Cronin, JW, Speizer, FE and Czeisler, CA. Extended Work Duration and the Risk of Self-Reported Percutaneous Injuries in Interns. JAMA 2006; 296:1055-1062.
  12. Barger LK, Ayas NT, Cade BE, Cronin JW, Rosner B, Speizer FE, Czeisler CA. Impact of Extended-Duration Shifts on Medical Errors, Adverse Events, and Attentional Failures. PLoS Med. 2006; 3(12):e487.
  13. Lockley SW, Landrigan CP, Barger LK, Czeisler CA. When Policy Meets Physiology: The Challenge of Reducing Resident Work Hours. Clin Orthop Relat Res. 2006; 449:116-127.
  14. Lockley SW, Barger LK, Ayas NT, Rothschild JM, Czeisler CA, Landrigan CP: Harvard Work Hours, Health and Safety Group. Effects of health care provider work hours and sleep deprivation on safety and performance. Jt Comm J Qual Patient Saf 2007; 33(11 Suppl):7-18.
  15. Landrigan CP, Czeisler CA, Barger LK, Ayas NT, Rothschild JM, Lockley SW; Harvard Work Hours, Health and Safety Group. Effective implementation of work-hour limits and systemic improvements. Jt Comm J Qual Patient Saf. 2007 Nov;33(11 Suppl):19-29.
  16. Fahrenkopf AM, Sectish TC, Barger LK, Sharek PJ, Lewin D, Chiang VW, Wiedermann BL, Landrigan CP. Rates of medication errors among depressed and burnt out residents: prospective cohort study. BMJ 2008; 336(7642):488-91.
  17. Landrigan CP, Fahrenkopf AM, Lewin D, Sharek PJ, Barger LK, Eisner M, Edwards S, Chiang VW, Wiedermann BL, Sectish TC.  Effects of the accreditation council for graduate medical education duty hour limits on sleep, work hours, and safety. Pediatrics 2008; 122(2):250-8.
  18. Barger LK, Lockley SW, Rajaratnam SM, Landrigan CP. Neurobehavioral, health, and safety consequences associated with shift work in safety-sensitive professions. Curr Neurol Neurosci Rep. 2009 Mar;9(2):155-64. Review.
  19. Cappuccio FP, Bakewell A, Taggart FM, Ward G, Ji C, Sullivan JP, Edmunds M, Pounder R, Landrigan CP, Lockley SW, Peile E; Warwick EWTD Working Group. Implementing a 48 h EWTD-compliant rota for junior doctors in the UK does not compromise patients' safety: assessor-blind pilot comparison. QJM. 2009 Apr;102(4):271-82.
  20. Rothschild JM, Keohane CA, Rogers S, Gardner R, Lipsitz SR, Salzberg CA, Yu T, Yoon CS, Williams DH, Wien MF, Czeisler CA, Bates DW, Landrigan CP. Risks of complications by attending physicians after performing nighttime procedures. JAMA. 2009 Oct 14;302(14):1565-72.
  21. Blum AB, Raiszadeh F, Shea S, Mermin D, Lurie P, Landrigan CP, Czeisler CA. US public opinion regarding proposed limits on resident physician work hours. BMC Med. 2010 Jun 1;8:33.
  22. Levine AC, Adusumilli J, Landrigan CP. Effects of reducing or eliminating resident work shifts over 16 hours: a systematic review. Sleep. 2010 Aug;33(8):1043-53.
  23. Gordon JA, Alexander EK, Lockley SW, Flynn-Evans E, Venkatan SK, Landrigan CP, Czeisler CA; Harvard Work Hours, Health, and Safety Group (Boston, Massachusetts). Does simulator-based clinical performance correlate with actual hospital behavior? The effect of extended work hours on patient care provided by medical interns. Acad Med. 2010 Oct;85(10):1583-8.
  24. Rajaratnam SM, Barger LK, Lockley SW, Shea SA, Wang W, Landrigan CP, O'Brien CS, Qadri S, Sullivan JP, Cade BE, Epstein LJ, White DP, Czeisler CA; Harvard Work Hours, Health and Safety Group. Sleep disorders, health, and safety in police officers. JAMA 2011; 306 (23):2567-78.
  25. Blum AB, Shea S, Czeisler CA, Landrigan CP, Leape L. Implementing the 2009 Institute of Medicine recommendations on resident physician work hours, supervision, and safety. Nat Sci Sleep. 2011 Jun 24;3:47-85.
  26. Gordon MB, Sectish TC, Elliott MN, Klein D, Landrigan CP, Bogart LM, Amrock S, Burke A, Chiang VW, Schuster MA. Pediatric residents' perspectives on reducing work hours and lengthening residency: a national survey. Pediatrics. 2012 Jul;130(1):99-107.
  27. Barger LK, Ogeil, RP, Drake, CL, O'Brien CS, Ng, KT, Rajaratnam SWM. Validation of a Questionnaire to Screen for Shift Work Disorder. SLEEP. 2012; 35(12): 1693-1703
  28. Barger L; Quan SF. A movement to promote healthy sleep: the case for corporate involvement. J Clin Sleep Med 2013; 9(8):739-740.
  29. Crowley KE, Rajaratnam SM, Shea SA, Epstein LJ, Czeisler CA, Lockley SW; Harvard Work Hours, Health and Safety Group. Evaluation of a single-channel nasal pressure device to assess obstructive sleep apnea risk in laboratory and home environments. J Clin Sleep Med. 2013 Feb 1;9(2):109-16.
  30. Evaluation of a Single-Channel Nasal Pressure Device to Assess Obstructive Sleep Apnea Risk in Laboratory and Home Environments Kate E. Crowley, Shantha M.W. Rajaratnam, Steven A. Shea, Lawrence J. Epstein, Charles A. Czeisler, Steven W. Lockley, for the Harvard Work Hours, Health and Safety Group J Clin Sleep Med. 2013 Feb 15; 9(2): 109–116. Published online 2013 Feb 15. doi: 10.5664/jcsm.2400 PMCID: PMC3544377
  31. Cohen IG, Czeisler CA, Landrigan CP. Making residency work hour rules work. J Law Med Ethics. 2013 Spring;41(1):310-4.
  32. Kevat DA, Cameron PA, Davies AR, Landrigan CP, Rajaratnam SW. Safer hours for doctors and improved safety for patients. Med J Aust. 2014 Apr 21;200(7):396-8.
  33. Sleep and cognitive function of crewmembers and mission controllers working 24-h shifts during a simulated 105-day spaceflight mission Barger L.K., Wright Jr. K.P., Burke T.M., Chinoy E.D., Ronda J.M., Lockley S.W., Czeisler C.A. (2014)  Acta Astronautica,  93 , pp. 230-242.
  34. Quan SF, Barger LK. Brief review: sleep health and safety for transportation workers. Southwest J Pulm Crit Care. 2015;10(3):130-9
  35. Ftouni S, Sletten TL, Nicholas CL, Kennaway DJ, Lockley SW, Rajaratnam SM. Ocular Measures of Sleepiness Are Increased in Night Shift Workers Undergoing a Simulated Night Shift Near the Peak Time of the 6-Sulfatoxymelatonin Rhythm. J Clin Sleep Med. 2015 Jun 11. pii: jc-00268-14.
  36. Barger, LK, Rajaratnam, SMW, Wang, W, O’Brien, CS, Sullivan, JP, Qadri, S, Lockley, SW, Czeisler, CA.. Common Sleep Disorders Increase Risk of Motor Vehicle Crashes and Adverse Health Outcomes in Firefighters. J Clin Sleep Med. 2015 Mar 15;11(3):233-40.
  37. Czeisler, CA. Duration, timing and quality of sleep are each vital for health, performance and safety. Sleep Health: Journal of the National Sleep Foundation, Vol. 1, Issue 1, p5–8
  38. Barger, LK, O’Brien, CS, Rajaratnam, SM, Qadri, S, Sullivan, JP, Wang, W, Czeisler, CA, Lockley, SW. Implementing a sleep health education and sleep disorders screening program in fire departments: a comparison of methodology. Journal of Occupational and Environmental Medicine. 2016 Jun;58(6):601-9. doi: 10.1097/JOM.0000000000000709.
  39. Sullivan JP, O'Brien CS, Barger LK, Rajaratnam SMW, Czeisler CA, Lockley SW. Randomized, prospective study of the impact of a sleep health program on firefighter injury and disability. Sleep. 2017 Jan 1;40(1). PMID: 27692049.
  40. Law-based arguments and messages to advocate for later school start time policies in the United States Lee C.J., Nolan D.M., Lockley S.W., Pattison B. (2017)  Sleep Health,  3  (6) , pp. 486-497.
  41. Is 8:30 a.m. Still Too Early to Start School? A 10:00 a.m. School Start Time Improves Health and Performance of Students Aged 13–16 Paul Kelley, Steven W. Lockley, Jonathan Kelley, Mariah D. R. Evans Front Hum Neurosci. 2017; 11: 588. Published online 2017 Dec 8. doi: 10.3389/fnhum.2017.00588 PMCID: PMC5727052
  42. Weaver MD, Vetter C, Rajaratnam SMW, O’Brien CS, Qadri S, Benca RM, Rogers AE, Leary EB, Walsh JK, Czeisler CA, Barger LK. Symptoms of sleep disorders, depression, and anxiety are associated with adverse safety outcomes in healthcare workers. Journal of Sleep Research. 2018 Aug 1:e12722
  43. Ogeil RP, Barger LK, Lockley SW, O'Brien CS, Sullivan JP, Qadri S, Lubman DI, Czeisler CA, Rajaratnam SMW. Cross-sectional analysis of sleep-promoting and wake-promoting drug use on health, fatigue-related error, and near-crashes in police officers. BMJ Open. 2018 Sep PMCID:PMC6150149.