Shift-Work Fatigue in the Petroleum Industry: A Proactive Countermeasure Using Light Cues
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Insomnia is a common problem in offshore shift-work environments. In rotating shift-work environments, daylight and darkness cues are incongruent with sleep and work schedules. As a result, many shift workers find it hard to adapt to the schedule, resulting in suboptimal sleeping patterns and increased workforce fatigue. This paper presents a scientific method for reducing fatigue risks in oil and gas organizations that operate a slowly rotating shift schedule.
Sleep and Fatigue in Offshore Shift-Work Environments
Humans are diurnal (i.e., day animals); because of this, our circadian rhythm is programmed to ensure that alertness, concentration, and other aspects relating to job performance are highest during the day. Our circadian rhythm makes us feel sleepy in the evenings and ensures that we can maintain restorative sleep during the night. The bodily processes related to this are maintained in the suprachiasmatic nucleus (SCN), which is in the anterior hypothalamus in the brain and is synchronized with the day/night cycle. During the abrupt transition to an offshore 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.
Circadian misalignment also takes place during travel, but, in the case of jet lag, the time-of-day cues at our destination—particularly daylight that contains blue short-wavelength light—enables our biorhythm to realign with the schedule. These time cues include
- A start-of-the-day cue in the form of bright blue (day) light in the morning
- A night cue in the form of the absence of this type of light, 3 hours before bedtime
During offshore night shifts, these time cues are missing or completely reversed. As a result, some shift workers only partially adjust to the imposed shift-work schedule. These circadian-misaligned shift workers have to work when their body prepares for sleep and have to go to bed when their body tells them to stay active.
Performance and Safety. Shift workers’ bodies are preparing for sleep when their schedule demands work, leading to significantly lower performance. This is supported by an increasing number of studies that show that alertness, cognitive capacity, and vigilance of unadapted shift workers are impaired. Job performance suffers as well, leading to a decreased work rate, more quality-control errors, and accidents. An elaborate meta-analytic study has shown that unadapted shift workers have almost a third greater risk of work-related accidents.
When shift workers are not able to obtain consistently their required number of hours of sleep after their shifts, a chronic sleep debt begins to accumulate. With each period of insufficient sleep, cognitive performance deteriorates further.
Health and Well-Being. Shift workers not only suffer from problems with performance, they also are at an elevated risk of several health problems. Prominent health problems among shift workers include sleep disorders (which can become chronic), obesity, gastrointestinal disease, increased incidence of cardiovascular disease such as heart attacks and strokes, and an increase of late-onset diabetes. These increases in risk are largely caused by the fact that the metabolic and digestive circadian systems are not able to adapt fully to the new sleep/wake schedule. For instance, unadapted shift workers produce 17% less leptin, a hormone that controls appetite and produces the feeling of being full. This increased appetite, combined with the high availability of caloric food in offshore canteens, may result in obesity.
Current Reactive Health and Safety Strategies. Many shift-work organizations focus solely on the treatment of symptoms of the night-work health and safety hazards (strategies such as providing sleeping pills, caffeine, programs that support healthy eating, and fitness programs). Most of these interventions, while better than nothing, do not address the underlying cause of the problem, which is circadian misalignment. Studies have shown that controlling light/dark exposure patterns (rather than sleep schedules) determines circadian phase and can help reduce circadian misalignment.
The Problem With Normal Offshore Light Exposure
Standard artificial lighting that can be found on many offshore platforms is not sufficient to align the biological clock to a new schedule. A third type of photoreceptor was discovered in the retina of mammals in 2001. This specific receptor is the main controller of the timing of the circadian system and reacts to light wavelengths of 460–490 nm (bright blue). This required wavelength is found in both bright blue daylight and artificial light but is exponentially lower in intensity in the latter, too low to be sufficient to provide the strong morning light cue needed to reset the biological clock efficiently. In addition, in night-shift environments, daylight and dark cues are incongruent to the sleep and work schedule.
Proactive Fatigue Countermeasures
The performance innovation described in this paper, called Night Fit, is based on previously applied solutions. The method is light-treatment-based and aimed at offshore shift-work environments. It optimizes work performance, health, and safety by improving sleeping patterns, which helps reduce workforce fatigue and, subsequently, human errors. Special glasses and energy lights are used that, when applied correctly, have a positive effect on the secretion of sleep hormones and workforce energy levels. This, in turn, will support effective off-shift recovery and adaptation to shift changes without the help of medication.
Managing Light Exposure. Because light is the primary signal to our bodies whether it is time to be active or to rest, specialized lights containing high levels of energy with the critical blue wavelengths (the SCN has a peak response centered around approximately 450–480 nm) and blue-blocking glasses were used to synchronize the light cues received by workers with their sleep/wake schedules. Findings from light-treatment studies show that this measure—when applied correctly—leads to a quicker and more complete adaptation to the shift-work schedule.
Several studies demonstrate that, by blocking blue light during scheduled sleep times, the production of melatonin, a sleep hormone and a potent antioxidant, is improved.
Timing of the light exposure determines whether the circadian rhythm of a shift worker is advanced (i.e., the individual is helped to sleep earlier) or delayed (i.e., sleep is postponed). When circadian-phase advance is desired, bright light should be administered immediately after waking and the worker should avoid exposure to artificial light—especially that containing the key blue wavelengths—in the 1–2 hours before bedtime by wearing the blue-blocking glasses.
Offshore guidance and training was provided to consider these bright-light-treatment factors. The project involved supporting crew members with two workshops on how to use the light-treatment strategies during offshore shift-work operations.
Sleep-Hygiene Training. For the bright-light strategies to be effective, the shift workers need to be educated regarding their appropriate use. During the project, two 1-hour offshore workshops were provided to the crew to raise awareness, create knowledge, and teach skills concerning sleep hygiene and the sleep-enhancing strategies. In addition, those workers reporting particular sleep problems were provided with further instructions to address the particular problems they reported.
Recent Project Example
Solitaire Project. In order to reduce fatigue-related risks and to enhance shift-work performance, health, and safety, Allseas decided to implement the Night Fit intervention program onboard its pipe-laying vessel Solitaire. In total, 169 shift workers were trained to make use of the Night Fit method.
In November 2015, 80 shift workers participated in the first phase of the project. No selection was made before the study; individuals with and without sleeping difficulties could apply for participation. Questionnaires were used to assess sleep quality before and after the intervention. Fifty-seven shift workers completed the questionnaires during the follow-up study, which took place 6 months after the initial intervention.
Self-Reported Effects of Intervention. The number of shift workers who labeled their sleep quality to be “very good” increased from 15% before the intervention to 41% during the follow-up 6 months later. Workers reporting a sleep quality of “fairly bad or worse” decreased from 25 to 4%.
A paired-sample t-test indicated that subjective sleep-quality scores (on a 10‑point scale) were significantly higher after the intervention than before. Reported sleep quality of 8 or higher increased by a factor of three (from 21% before the intervention to 62% 6 months after the implementation of Night Fit). The number of shift workers with a sleep quality grade of 5 or lower decreased from 34 to 13% (Fig. 1).
No Silver Bullet
The application and the efficacy of a light-treatment intervention will depend on many factors, such as the quality of the workshops, the type of working schedule, the working environment, the sleeping environment, selection criteria of the participants, and the commitment of the vessel-management team. It cannot simply be enforced as a policy but requires active participation by workshop attendees. In order to scale up this proactive fatigue-countermeasures approach for large oil and gas organizations, a train-the-trainer initiative is available. For fast-rotating shifts, completely reducing circadian misalignment is impossible because the body clock cannot phase shift fast enough. Especially in onshore environments, this type of shift system is very common, but it is far from optimal because of the performance, safety, and health problems it creates. However, if the rotation is relatively slow (i.e., 10 days or longer without a rotation), then light treatment can be applied as an effective tool to enhance sleep quality and reduce circadian misalignment.
Shift-Work Fatigue in the Petroleum Industry: A Proactive Countermeasure Using Light Cues
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