The Safety Potential of Real-time Measurements of Mental Fatigue

Published Sept. 26, 2018

By Kay Bechtold

With his background in mining, Rustin Reed has seen firsthand how certain jobs can be both mentally and physically straining. Some employees of a mine he used to work at would commute by motorcycle from one to two hours away, work a 12-hour shift driving a haul truck, and then drive themselves home. Now an assistant professor of safety science at Embry-Riddle Aeronautical University in Prescott, Ariz., Reed helps develop approaches for monitoring worker fatigue. He shared some of his experiences in a session on real-time exposure measurement at the 11th Annual Scientific Conference of the International Occupational Hygiene Association in Washington, D.C.

“There are a lot of things that we ask workers to do, especially as our society becomes modernized and global, that really can strain people—their physiology and also their cognition,” Reed told attendees.

Occupational hygiene professionals can monitor fatigue using mathematical modeling and by screening workers to determine their fitness for duty. Reed’s presentation focused on real-time monitoring approaches for fatigue, which can be used to predict worker fatigue and prevent fatigue-related events such as industrial accidents. Current technology intended to measure fatigue in real time relies on research that has demonstrated that fatigue can be measured by changes in the power of the alpha, theta, gamma, and delta bands of an electroencephalogram, or EEG, which records electrical activity of the brain.

Reed described a small pilot study conducted at a mine in South America that sought to determine whether he and his team could accurately estimate workers’ fatigue using external physiology alone. Study participants wore a BioHarness—a monitor and strap attached around the chest—that tracked 14 physiological measures, including heart rate, respiration rate, and an electrocardiogram estimate. They also wore a device called a SmartCap, a headband that measures EEG on five channels. Reed explained that the device produces a fatigue score on the Oxford sleep resistance scale. Scores range from one to five, with one representing someone who is “bouncing off the walls” and five representing someone who is clinically asleep. Reed described a score of two as normal, three as also normal but showing signs of sleepiness, and four as indicating a high risk for “micro sleep.” The devices provide real-time feedback, alerting individuals who score higher on the scale. Researchers distributed bands to employees and educated them about what the readings meant. Since there was no formal fatigue risk management system in place at the mine, all fatigue management was self-imposed by the workers.

Reed and his team saw a small amount of improvement throughout the study.

“We think simply by providing real-time feedback to these workers, they took steps and found ways to reduce their own [fatigue] scores,” Reed said. “It’s not a huge improvement, but I think it speaks to the power of real-time feedback for someone to adjust behaviors and improve.”

An unexpected outcome of the study was that 22 individuals who continued to receive high scores consulted with health professionals and were diagnosed with obstructive sleep apnea, or OSA. While identifying individuals with OSA wasn’t an intent of the study, Reed described it as a welcome byproduct of implementing the monitoring devices.

The fatigue monitor can be a part of a fatigue risk management system, but Reed stressed that it’s only part of the solution. Occupational hygienists should keep a number of factors in mind when choosing a monitoring technology, including whether the tool will allow them to scale to other equipment and whether it complies with local legislation regarding individuals’ privacy. Companies are all different, and Reed urged attendees to make sure that technology will work with their equipment and work sites.

Expense, acceptance, and convenience are other aspects of technology that should affect hygienists’ decisions regarding new tools. Depending on how many devices are needed and what the application is, certain technologies can be expensive. These tools also require employee buy-in, which, Reed noted, isn’t always easy to acquire. For example, some participants in his pilot study didn’t want to be seen wearing a headband. The device Reed chose to use can be worn alone or integrated into a hardhat or baseball cap. Anecdotally, a supervisor’s acceptance of new technology is the number-one factor in the success of new initiatives, Reed said.

Looking ahead, Reed and his team hope to develop a simple model to assist companies in selecting fatigue monitoring solutions. He is also interested in developing a system as simple as a fitness tracker that can estimate fatigue and other physiological measurements such as core body temperature in real time.

“I think the sky is the limit with the way technology is advancing,” Reed said. “Some of these things will happen soon.”

Kay Bechtold is senior editor of The Synergist.

Mention of specific products does not constitute endorsement by AIHA or The Synergist.

IOHA is an association of industrial and occupational hygiene associations from around the world. AIHA hosted IOHA’s 11th International Scientific Conference from Sept. 24 to 26 at the Marriott Marquis hotel in Washington.