Published research and presentations by our team of PhDs and MDs.
Fortune 500® companies that have worked with CIRCADIAN®
Continents on which CIRCADIAN® has provided 24/7 workforce solutions


CIRCADIAN® is the global leader in providing 24/7 workforce performance and safety solutions for businesses that operate around the clock.  Through a unique combination of consulting expertise, research and technology, software tools and informative publications, CIRCADIAN helps organizations in the 24-hour economy optimize employee performance and reduce the inherent risks and costs of their extended hours operations.

Working from offices in North America, Europe, Asia, and Australia, CIRCADIAN experts ensure that over half the Fortune 500, and other leading international companies, improve their competitiveness in the global 24/7 economy. CIRCADIAN’s core expertise is the staffing, scheduling, training, and risk management of their most vital asset – the 24/7 workforce.

Founded in 1983 by Dr. Martin Moore-Ede, a former professor at Harvard Medical School and author of the best-selling book The Twenty-Four Hour Society, CIRCADIAN has led the development of innovative new technologies and tools to enable employees to successfully adapt to today’s high performance 24/7 workplace.

  • Proven change management process for determining and implementing site-specific, optimal shift schedules.
  • Support companies as they expand from a 5-day to a continuous 24/7 operation, including strategy and business case development and employee change management approaches.
  • Determine optimal staffing and crewing levels and managing overtime.
  • Create win-win scheduling solutions for management, unions, and employees.
  • Recognized leader in fatigue risk management consulting and technology.
  • Expert support of  government and industry associations in developing fatigue risk management standards.
  • Assist clients in complying with industry fatigue management regulations.
  • Provide tools, technologies, systems, strategies, and consulting in the implementation and management of Fatigue Risk Management Systems.
  •  Provide analytical software tools for fatigue risk root cause analysis of incidents and accidents, and assessment of fatigue risk in the work schedule.
  • Seminars and workshops for managers and supervisors on shift schedule optimization, staffing, and fatigue risk management system implementation.
  • Fatigue risk training programs (classroom, Train-the-Trainer, online) for employees and supervisors.
  • Educational support materials on shiftwork and fatigue (newsletters, booklets, videos).
  • Management reports and industry best practices surveys for 24/7 operations.
  • Gap analyses and fatigue risk assessments of 24/7 operations.
  • Development of innovative technologies to assess and improve the alertness, performance, health, and safety of the 24/7 workforce.
  • Cost analyses and benchmarking of Key Performance Indicators (absenteeism, turnover, overtime, productivity, safety).
  • Extensive databases of shiftwork policies, practices, and schedules.
  • Evaluating new technologies for monitoring and improving employee alertness.


Martin Moore-Ede

Chairman & Chief Executive Officer


For over 40 years, Dr. Moore-Ede has been a leading expert on circadian clocks and the health consequences of circadian disruption by light. As a professor at Harvard Medical School (1975 – 1998), he led the team that located the suprachiasmatic nucleus, the biological clock in the human brain that controls the timing of sleep and wake, and pioneered research on how the human body can safely adapt to working around the clock.

In 1983 Dr Moore-Ede founded the global consulting and technology firm, CIRCADIAN® (www.circadian.com) which optimizes 24/7 workforce productivity, health and safety with a client base that includes over half of the Fortune 500. To address his clients’ growing concerns about the harmful effects of conventional fluorescent and LED lighting on workplace health, safety and performance, Dr Moore-Ede founded the Circadian Light Research Center in 2010. He then spun off CIRCADIAN ZircLight in 2011 to develop evidence-based LED circadian lighting systems that provide physiologically optimized light spectra across day and night based on comprehensive medical research and a proprietary IP portfolio. Korrus acquired the lighting assets of CIRCADIAN ZircLight in 2022, and Dr Moore-Ede became Chief Medical Advisor of Korrus.

Dr. Moore-Ede graduated with a First Class Honors degree in Physiology from the University of London and received his medical degrees from Guy’s Hospital Medical School, and his Ph.D. in Physiology from Harvard University. He has published 10 books, and more than 180 scientific papers on the physiology of the circadian system, interaction with environmental light and the consequences of circadian disruption including human fatigue, errors, and accidents. Dr. Moore-Ede holds multiple patents on assessing and mitigating circadian disruption and fatigue.

He has served on multiple national and international committees and has received numerous awards including the Bowditch Lectureship of the American Physiological Society. He is a frequent guest on television (CNN, Today Show, Good Morning America, 20:20, Dateline, Oprah Winfrey, Nova, BBC), radio (NPR Fresh Air, Connection), and print media (Wall Street Journal, New York Times, Washington Post, Time, and Newsweek). He has testified before Congressional committees on multiple occasions and advised government agencies on the health and safety of the 24/7 workforce in the US, Canada, and Europe.

Andrew Moore-Ede



Andrew Moore-Ede, an internationally recognized expert in 24/7 workforce management, leads the consulting organization at CIRCADIAN®. Over the past three decades, Andrew has managed projects with some of the largest organizations in the world, including government agencies and Fortune™ 500 companies to improve the health, safety, and performance of their 24/7 workforce.

Andrew has deep experience in guiding management and employees through a win-win change management process to create the optimal path to the best shiftwork, shift scheduling and fatigue risk management solutions. These projects have included implementing the optimal shift schedule, helping companies expand to 24/7 operations, developing shiftwork health & safety training programs, conducting risk assessments, and designing customized fatigue risk management plans and systems. He is also a popular speaker at industry conferences and corporate workshops on best 24/7 workforce management practices.


Bill Davis

Vice President of Operations


Bill is responsible for management oversight on all global consulting projects for CIRCADIAN®, ranging from workforce management, to scheduling optimization, to shiftworker staffing, crewing, and training, to overtime management, and to employee health, safety, and productivity initiatives.

In addition to his personal involvement in hundreds of shiftwork-related projects, Bill has extensive experience with fatigue management programs and human error reduction initiatives. These projects have been as diverse as evaluating the effects of high-altitude mining (5000+ meters in the high Andes) on the health, safety, and performance of heavy equipment operators, to analyzing the physiological and sociological effects of working 24-hour shifts in a large, metropolitan emergency medical response force - utilizing state-of-the-art, automated fatigue detection and countermeasure devices in each case. This broad array of experience has made him a highly sought-after speaker at industry forums and conferences.

Prior to his tenure at CIRCADIAN®, Bill spent 10 years with International Paper as a Corporate Safety Manager and as a Plant Manager. He also spent a decade with Jones and Laughlin/LTV Steel, starting as a steel mill shiftworker and working his way up the safety management ranks. This real-world industrial background has provided Bill with a natural rapport with managers, union representatives, and employees at all organizational levels.

Fran Sullivan

Chief Operating Officer
Chief Financial Officer


Fran Sullivan serves as Chief Operating Officer and Chief Financial Officer of the CIRCADIAN® Companies. Mr. Sullivan’s responsibilities at CIRCADIAN® include coordinating marketing, sales, and operations to drive revenue growth. He is also responsible for  managing the Company’s intellectual property portfolio and providing financial, tax, and human resource management. Mr. Sullivan has deep experience in software, SAAS, and technology businesses. Previous positions include Senior Manager at KPMG  and Director of Finance at Avid Technology (NASDAQ: AVID). Mr. Sullivan holds his undergraduate degree from the Carroll School of Management at Boston College (where he later served as an adjunct professor) and his MBA from Northeastern University


Irene Fassler

Vice President


For more than 18 years at CIRCADIAN®, Irene Fassler has led the multi-disciplinary team of experts and consultants in the expert witness division, conducting comprehensive investigations of high-profile accidents and other insurance claims where fatigue has been alleged. In addition, to managing the investigations in all modes of transportation and other industries including steel mills, construction, and public safety, Irene and the team have supported petitions involving regulatory change for multiple marine pilot associations and public transit organizations. Almost all of the investigations and regulatory petitions have required preparing detailed reports backed by data analysis and circadian science.

In her role as a senior manager at CIRCADIAN®, Irene has also been the lead on a variety of complex, multi-phase international projects involving circadian sleep management, fatigue risk analysis and the development, implementation, and assessment of customized Fatigue Risk Management Systems in industrial and transportation 24/7 operations. Irene successfully blends complementary skills from both her legal and social work background to provide excellent customer service with strong analytical, communication and listening skills. 

Prior to her work at CIRCADIAN®, Irene practiced law and was a member of multiple research teams at Boston University School of Social Work and Boston College School of Management where she co-authored a number of peer-reviewed publications, conducted subject interviews and coordinated a faculty development grant.

Sam Sirois

Manager of Consulting Services


With over 24 years’ experience in assisting over 500 clients, Mr. Sirois' primary client base includes public utilities, petroleum based refineries, mining companies, transportation, manufacturing facilities in the bio-tech, chemical, automotive, pulp & paper, food & beverage, plastic, and printing industries, as well as professional sports operations.

In this position within CIRCADIAN® Technologies' Operations Department, Sam is responsible for the development, presentation, and implementation of employee training programs, alternative work schedules, staffing level analyses, workload assessments, fatigue risk assessments and comprehensive Fatigue Risk Management Systems (FRMS) programs. He is also responsible for providing management seminars and workforce training on subjects, such as, sleep and fatigue, shift scheduling, Fatigue Risk Management Systems, and control room environmental design to improve alertness.

After developing a physiology-based safety and health training program for shiftworkers titled Managing a Shiftwork Lifestyle (MSL), Mr. Sirois has been the lead trainer for CIRCADIAN®, working directly with employees and also with corporate trainers for CIRCADIAN®’s Train-The-Trainer (TTT) program. The results of both employer and employee follow-up assessments clearly indicate that CIRCADIAN®’s lifestyle training has provided measurable benefits for both the company, its employees, and their families, including improved alertness levels, health, and quality of life, along with reduced accidents and reduced overall operating costs. Mr. Sirois’ training program was also used as the basis for an interactive CD-ROM training program titled Extended Hours Employee Training: Health & Safety, which was designed specifically for the Global Drilling Safety Leadership Initiative to help improve the health and safety of offshore oil rig workers, as well as a training program titled Managing a Mining Lifestyle produced for Caterpillar and its clients in the mining industry. Mr. Sirois has also developed and presented sleep and fatigue management training programs to non-shiftwork companies, such as Sony Pictures Athletic Club, Indianapolis Colts, Pittsburgh Pirates, Texas Rangers, Indianapolis Pacers, and has presented at Major League Baseball’s Winter Meetings twice.

A few of his industrial clients include Frito-Lay, Cargill, General Mills, ConAgra Foods, Red Stripe Brewery, Michelin Tire, Borg Warner, Toyota, Honda, Bayer Material Sciences, Unilever, Proctor and Gamble, Thermo Fisher Scientific, Bayer, Siemens, SC Johnson, Quad Graphics, Caterpillar, BHP Billiton, Freeport-McMoRan, International Paper, Georgia Pacific, ChevronTexaco Pipelines, Shell, BP, Cheniere, DC Water and Sewer Authority, Barrick Gold, Great River Energy, Princeton University Energy Operations, Cabot Corporation, Lyondell-Basell, Sunoco Logistics, Constellation Energy, Eversource, Eaton Corporation, Global Ethanol, and Suncor.



Rainer Guttkuhn

Technical Manager


Rainer Guttkuhn has been designing and coding software for the data analysis of operational data from several North American railroad companies. In this capacity,  he has developed a circadian alertness simulation (CAS) software package that can be used to compare different work-preparation strategies to a given work schedule.

As a Software Engineer at CIRCADIAN® Technologies, Inc. (CTI), Mr. Guttkuhn has been designing and coding software for the data analysis of operational data from several North American railroad companies. He designed and coded a crew utilization simulation in Delphi, which is used to design and simulate crew schedules that offer North American freight train engineers the opportunity to predict their hours of duty and therefore to prepare for duty. These scheduling projects are part of the initiatives of the railroad companies to improve safety within their operations.

Additionally, Mr. Guttkuhn developed a circadian alertness simulation (CAS) software that is used to determine and visually chart the impact of any given work-sleep-pattern on alertness. This tool can be used to compare different work-preparation strategies to a given work schedule. The software uses algorithms and rules that were developed by Mr. Guttkuhn to fit certain circadian rhythms and combines them with individual physical parameters.

Mr. Guttkuhn is part of the schedule development group that designs schedules for transportation clients, such as CN Rail. At CN, for example, he spends time both in the lab and on-site working with union and management representatives in order to adapt the software to given operational requirements, as well as other site-specific considerations as they arise.

Mr. Guttkuhn brings solid people skills to his work in addition to a superior technical skillset. This is important, as he is often interacting with various project team members. As part of the schedule development and implementation for the CPSoo railroad, for example, Mr. Guttkuhn is often on-site and involved in the process of implementing crew schedules. His involvement at CP has included being on-site for the first weeks after the transition from the old to new schedule in order to give technical advice during this crucial transition period. Mr. Guttkuhn is fortunately able to effectively communicate highly technical information in language that labor and management can work with. This is critical to the success of the operation, as the comfort level of the employees is strongly related to the success of the project.




Working from our home office north of Boston, our core team supports operations is North America, Europe, Australia, Asia and South America, including more than half the Fortune 500, and many other leading companies workdwide. We currently have the following opportunities: