Dr. Fran Pilkington-Cheney presented her research in fatigue and sleepiness in bus drivers for SAFTE-FAST’s third webinar in the FAST Talk series on November 15, 2024. Dr. Pilkington-Cheney is a Lecturer in Psychology and Sleep at Nottingham Trent University, UK. Her research focuses on sleepiness and fatigue within safety-critical tasks like shift work and transportation. She worked for several years as a fatigue risk management researcher focusing on aviation before joining the Transport Safety Research Centre at Loughborough University. Dr. Pilkington-Cheney’s research explores sleepiness and fatigue in real-world settings, like tunneling and construction, driver state monitoring, fatigue detection and intervention, fitness-to-drive, and countermeasures for fatigue and sleepiness for London city bus drivers, with a specific focus on the use of sugar.
Dr. Pilkington-Cheney’s talk covered the basics of fatigue and sleepiness in the context of transportation before launching into a discussion about effective and ineffective countermeasures for sleepiness in bus drivers. The general public frequently uses the terms sleepiness and fatigue interchangeably, but they do represent different concepts. Fatigue describes the overall state of reduced performance capability as a result of sleep loss, circadian misalignment, or workload[1]. Sleepiness refers to the physiological likelihood of falling asleep. Bus drivers falling asleep at the wheel is a serious safety hazard, so it is important to know what works (and what doesn’t) to keep drivers awake throughout their routes.
On the effective side of countermeasures for sleepiness, there are few surprises. Adequate sleep, caffeine, and rest stops are effective. You probably already knew that. What may be surprising is how workplace restrictions limit London bus drivers from employing these countermeasures. First of all, most of London’s buses run 24 hours a day[2]. Adequate sleep is difficult for shift workers[3], and night driving is associated with sleepiness even when individuals aren’t dealing with accumulated sleep debt[4,5]. Caffeine works well, but bus drivers cannot just go to the bathroom whenever they want. Could you imagine waiting at 6 AM for a big red double-decker bus to pick you up and take you to Heathrow Airport (I may be drawing from personal experience here), but when the bus pulls up, the driver hops off and bolts into a public restroom? (For reference, that is not what happened to me. The bus driver in my story blew past my stop at top speed, leaving me forever with bus-related abandonment issues.) The relevant point is that bus drivers need to limit how much they need to pee during work hours and caffeine is a diuretic. The job could get pretty uncomfortable if the bus driver is chugging coffee to stay awake but has no access to a bathroom. Rest breaks are also difficult to squeeze in. Buses run on schedules and passengers can get awfully unruly when their bus is late. And, if the driver doesn’t have the ability to stop the bus for a break, then you can definitely rule out strategic napping as a viable sleepiness countermeasure.
Instead, drivers rely on some creative countermeasures that they can do within the confounds of their bus. Opening a window, talking to themselves, in-cab fragrances and sugar consumption are popular choices for counteracting sleep-related fatigue. Do they work? Not so well. In-vehicle fragrances may be an exception. A recent study by Dahlman et al. found that spraying perfume in a driver’s face if they started nodding off during a driver simulation helped wake the driver up[6]. Either smelling vanilla or a scent that directly stimulates the trigeminal nerve, allyl isothiocyanate (think mustard or wasabi), were moderately successful in alerting the driver. Of course, this intervention isn’t practical unless the driver has a friend willing to mist the air with Ariana Grande Cloud Eau de Parfum Spray if they close their eyes for too long. Perhaps in the future, in-cab monitoring systems could be rigged to produce alerting vanilla farts if a driver experiences a microsleep.
What about sugar? There is a public belief that sugar increases energy via the “sugar rush.” Parents may love to use this excuse to explain their children’s wild behavior, but the phenomenon of the sugar rush is a myth! Sugar does not affect the behavior or cognitive performance of children[7]. If you’re now wondering why your kids go nuts after eating Pixie Stix—it’s not the sugar that affects their behavior; it’s the expectation that the sugar will affect their behavior. On a personal note, telling your sugar-crazed 8-year-old that he is experiencing a placebo effect-- even if you show him figures from an academic meta-analysis supporting this conclusion—does very little to counteract that psychological foolishness. In adults, the simplest form of sugar, glucose, may affect cognitive performance in an inverted U-shaped dose-response curve, meaning that too little or too much glucose is bad for your ability to think. Glucose is found in fruit, honey, and corn and is frequently added to sugary drinks like grape juice or colas. In some parts of the world, fructose (ala the infamous high fructose corn syrup) is commonly used as a replacement sweetener for foods and drinks. Table sugar is called sucrose and is a combination of glucose and fructose. Less is known about the effects of fructose or sucrose on cognition[8]. A high-sugar diet is generally regarded as bad for one’s health[9].
As Dr. Pilkington-Cheney discussed in her talk, many drivers consume sugary snacks to stay alert because they need to do something to avoid falling asleep, and they can get away with munching on jelly beans more easily than they can by drinking coffee or taking a nap. Dr. Pilkington-Cheney recommended improving opportunities for rest breaks and sleep health education over the use of sugar to counteract sleep-related fatigue. She also introduced her newest project on the development and validation of sleep-related driving risk prediction tools in collaboration with the National Police Wellbeing Service. The aim of this project, called SleepiEst, is to reduce road crashes caused by sleepiness in the United Kingdom among shift-working police employees who either commute by driving or drive on duty. The data collected by this study will be used to develop a sleepiness risk prediction tool that will hopefully have applicability to the wider shift work and transport industries. You can learn more about SleepiEST here.
The next FAST Talk will be held on February 27 at 2:00 PM Eastern Standard Time. The speaker will be Dr. Olivia Walch, a researcher in the University of Michigan Department of Neurology and the CEO of Arcascope, a sleep and circadian rhythms technology start-up company. Dr. Walch is also the author of Sleep Groove, a myth-busting guide to sleep and circadian science. The FAST Talk series is open to the public; viewers can register to attend the talks live or watch recordings of earlier talks through the FAST Talk Hub.
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