Guest blog by Koos Meijer – KM Human Factors Engineering

Last month Koos Meijer (KM Human Factors Engineering) presented at the ATCE 2017 of the Society of Petroleum Engineers in San Antonio, Texas. In his presentation, Koos discussed a proactive fatigue countermeasures innovation ‘Night Fit’ which focuses on the timing, duration, intensity and color of light exposure to enhance sleeping patterns. This blog focuses on the science behind it and the implications it can have for process safety in offshore and other high-hazard industries.

The impact of sleep deficiency

Insomnia ranks as the second most common health complaint internationally and is a common problem in shift work environments. In the Netherlands between 42% and 68% of the shift work population copes with difficulties sleeping. Even though there are individual differences in how sleep-deficiency affects alertness and performance, nobody is immune from its effects. Fatigued people are less focused, think and move more slowly, make more mistakes, and can have memory difficulties. These effects reduce productivity and increase the risk of work-related errors and accidents.

A lack of sleep induce adverse changes in our brain and reduces cognitive performance. It impairs attention, vigilance and working memory and other functions, such as long-term memory and decision-making. These are all safety-critical aspects of human performance and process safety, poor sleep and fatigue should therefore be prevented at all times.

The main problem with shift work ‘circadian misalignment’

Our body is programmed to ensure that energy, alertness, concentration and other aspects relating to mental and physical performance peak during the day. Our internal biological clock makes us feel sleepy in the late evenings and ensures that we can maintain restorative sleep during the night. During the abrupt transition to a night working schedule, the sleep and wake timings of our biorhythm become misaligned with those of the work schedule; this is referred to as circadian misalignment, a mismatch between our internal circadian clock and work, sleep, and eating activities [Scheer et al., (2009)]. See also the figure below.

Shift workers who are circadian misaligned (i.e. not adapted to the shift work schedule) are, at least partially, active when their brain tells them to sleep while they have to go to bed when their brain tells them to remain active. This in turn, leads to a significant decrease in performance, health, safety and overall well-being.


Circadian misalignment also takes place when being jetlagged. However, in the case of jetlag, the new daylight exposure during work at our destination helps our circadian rhythm to recalibrate to the new time zone. In some cases that can take up to 12 days.

Offshore shift work schedules

During offshore operations, some shift workers work in night shifts for multiple weeks in a row. During these shifts, daylight exposure is missing or completely reversed. This makes it hard to completely adjust to the imposed shift work schedule [Waage, et al., (2009)]. This results in lowered sleep quality, high fatigue levels, and suboptimal performance, health and safety.

Fast rotating schedules

During fast rotating shifts (e.g. 3 or 4 night shifts consecutively), that are commonly applied in onshore locations, there is no way to completely reduce circadian misalignment. This is because our body clock cannot phase-shift fast enough. Without a constant sleep/wake schedule, the body’s internal biological rhythms may always remain out of sync [Scheer et al., (2009)]. Specific shift work mitigation strategies can be applied to these type of shift work environments.

An example of circadian misalignment: a mismatch between our internal circadian clock and work, sleep, and eating activities. In this example, you have to work when your brain tells you to sleep and have to go to bed when your brain tells you to remain active. Circadian misalignment leads to significantly lower performance, health, safety and overall well-being.

Current reactive offshore health and safety strategies

Many offshore shift work organizations focus solely on the treatment of symptoms of the shift work health and safety issues (strategies such as providing sleeping pills, caffeine, programs that support healthy eating, and fitness programs). These reactive strategies are depicted on the right side of the Fatigue Bowtie (a diagram that visualizes the risk you are dealing with in one, easy to understand picture). These interventions do not address the underlying cause of the shift work problem, which is circadian misalignment [Scheer et al., (2009)]. Studies have shown that controlling light-dark exposure patterns (rather than sleep schedules) determines the circadian phase and can help to reduce circadian misalignment [Appleman et al., (2013)].

Proactive fatigue countermeasures

The Night Fit method applies effective sleep enhancing strategies which help to increase the quality of sleep without the use of medication. One of these strategies employs timed light-exposure using special glasses and blue lights, which help to assist employees with synchronizing their biological rhythm with the work schedule. This achieves a more balanced fit between our internal clock and the work/sleep / eat schedules, resulting in enhanced sleeping patterns, energy, health, performance and safety. These factors are depicted on the left side of de Fatigue Bowtie.

The Night Fit strategies are taught to the employees during two interactive workshops: ‘Work Hard, Sleep Hard’. Special blue filtering glasses and portable energy lights are used which, when used and timed correctly, have a positive effect on the secretion of sleep hormones and energy levels. Enhanced sleep quality will help the workforce to fully recharge their brain and body prior to their shift, and thus increases their performance and resilience to fatigue risks.

Light treatment results in the Oil & Gas industry

At the latest Night Fit projects that were conducted offshore the crew reported to feel less fatigued, more alert, and more energized during their work. The number of participants reporting “very good” almost tripled and those reporting sleep quality of “fairly bad or worse” decreased by 75%.

“Last weeks I experienced deeper sleep and did not wake up so much as usually. Normally I get very little sleep and wake up quite often.”
– Scaffolder

“It works for me, since using it I sleep better and feel less tired, it’s comfortable for me to use. The last years before Night Fit it was very hard for me to get good sleep.”
– Mechanic

Enhancing employees’ potential with proactive fatigue management

Enhanced sleep quality will help the workforce to fully recharge their brain and body prior to their shift, and thus increases their performance and resilience to fatigue risks. It will result in an increase in focus and vigilance. As a result, human error risks will be reduced. All things considered, by improving sleep duration and quality, a safer and healthier work environment can be created. In order to scale up this proactive fatigue countermeasures approach for large organizations, a Night Fit train-the-trainer initiative is available.

No ‘silver bullet’

It has to be noted that at fast rotating nightshifts there is no way to completely reduce circadian misalignment. Specific sleep hygiene mitigation strategies can be applied to these type of shift work environments.

For any further information or inquiries about the application of light treatment at your organization, please contact Koos Meijer via


Scheer et al., (2009). Adverse metabolic and cardiovascular consequences of circadian misalignment,” Proceedings of the National Academy of Sciences of the United States of America, 106, 4453–4458.

Waage, et al., (2009). Shift work disorder among oil rig workers in the North Sea. Sleep, 32(4), 558-565.

Appleman et al., (2013). Controlling light-dark exposure patterns rather than sleep schedules determines circadian phase. Sleep medicine, 14(5), 456-461.