Shift-Work Fatigue in the Petroleum Industry: A Proactive Countermeasure Using Light Cues
Authors: Wilson Adam 
Published: October 2018

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 187048, “Shift-Work Fatigue in the Petroleum Industry: A Proactive Fatigue Countermeasure,” by Koos Meijer, KM Human Factors Engineering; Martin Robb, SPE, Human Factors Applications; and Jasper Smit, CGE Risk Management Solutions, prepared for the 2017 SPE Annual Technical Conference and Exhibition, San Antonio, Texas, USA, 9–11 October. The paper has not been peer reviewed.
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.