Exploring the use of individual countermeasures to sleepiness in the applied context of bus driving

Sleep is vital for individuals to be alert and perform effectively. However, it is reported that individuals often obtain less than the recommend hours of sleep, leading to instances of increased sleepiness. To manage this, people may use certain strategies to increase alertness. The focus of this thesis is on individual countermeasures to sleepiness, which are strategies an individual themselves can use. The literature highlights that caffeine and naps are effective at counteracting sleepiness although they are not the only countermeasures people use. Another strategy people may consider using is sugar. Existing research has reported inconsistent findings as to its alerting effects, with limited research using standardised sleepiness measures and protocols. Without evidence of its efficacy as a countermeasure, a reliance on sugar to promote alertness could have serious consequences, particularly during safety critical tasks such as driving or during shift work.

Sleepiness during safety critical tasks is dangerous. It is thought that sleepiness contributes to approximately 15-30% of global road traffic crashes and can result in injuries and accidents in the workplace. Sleepiness is prevalent amongst shift workers, with many safety critical occupations utilising shift work to maintain 24h services. One approach to the management of sleepiness within the workplace is higher-level, occupational countermeasures such as fatigue risk management and education, although these are out of control of the worker themselves. Workers may be able to implement individual countermeasures to alleviate sleepiness, however, ineffective measures (such as sugar) may offer little benefit. Overall, it is not clear what the prevalence of sugar use is to improve alertness, or whether it is beneficial as a countermeasure to sleepiness. If it is used regularly as a sleepiness countermeasure, it is not known why it is chosen over effective strategies, or whether there are any factors which predict this. Education about the effectiveness of countermeasures may improve safety by increasing the uptake of effective strategies, although it is unclear how feasible or practical this would be.

This thesis aims to explore the use of individual countermeasures to sleepiness with a specific focus on sugar and its use by shift working bus drivers. This was achieved by conducting a series of five research studies. Firstly, the everyday use, knowledge and expectation of sleepiness countermeasures was investigated in a survey of 314 participants from the general public. The results showed that individual sleepiness countermeasures were regularly used although knowledge and expectation of certain products varied. Importantly, sugar was regularly used to counteract sleepiness, with approximately one third of the sample stating a form of sugar would be more effective than caffeine at offsetting sleepiness. Following from this, a controlled repeated measures study was conducted to investigate the effects of a glucose drink (an ingredient in sports and energy drinks) on alertness (PVT) and subjective sleepiness (KSS) following five hour sleep restriction (N = 40). The glucose drink did not significantly increase alertness, either subjectively or by improving reaction time, compared to the placebo drink, demonstrating that glucose is potentially an ineffective sleepiness countermeasure. However, there was no indication of a worsening in performance following the glucose drink, suggesting that it does not exacerbate sleepiness.

Building on these initial findings, an applied use case was selected to investigate individual countermeasure across three studies. The bus industry was chosen because bus drivers are required to perform safety critical tasks around the clock and are also responsible for passenger and road user safety. Therefore, effectively managing sleepiness is vital. First, specific analysis of focus group data with 62 city bus drivers identified that several individual strategies were used to counteract sleepiness, including sugar, however sleepiness countermeasure use was heavily impacted by workplace restrictions (e.g., facility access, schedules, location of breaks). Second, a survey of bus drivers’ sleepiness countermeasure preference was used to identify factors which predicted the use of caffeine or sugar as an individual countermeasure (N=1353). Caffeine was chosen as the comparison to sugar based on the large quantity of literature which supports its effectiveness in alleviating sleepiness. Predictors of sugar included being female, having self-reported neutral health, actively doing something to keep awake and commuting by car. Predictors of caffeine included smoking, taking sleeping pills, increased sleep apnoea risk, access to indoor rest, regularly fighting sleepiness and previously having a close call due to sleepiness. Although there were differences, many of the significant predictors were similar. This potentially makes targeted interventions challenging or less likely to be successful. One potential solution to assist bus drivers in individual countermeasure use is increased education on the topic.

Finally, to explore how the findings from this research could be used to inform bus driver education relating to effective sleepiness countermeasures, online discussions and a two-stage Delphi survey were conducted with 10 experts in the bus industry. The results culminated in industry guidance in the form of considerations, which could be used when engaging with or implementing sleepiness countermeasure education. Within the considerations, 11 statements were deemed important and feasible according to experts, and 10 statements deemed important but less feasible, due to engagement from various stakeholders and longer timescales for implementation of initiatives. The guidance highlighted that the education should be broadened as part of a wider educational programme relating to fatigue and sleepiness, rather than being delivered in isolation. This education also needs to be delivered alongside the development of an open safety culture. Workplace environment was a barrier to effective countermeasure use, and unlikely to change in the short term, however it is essential that bus drivers know what will be effective at alleviating sleepiness so as not to rely on ineffective measures during safety critical tasks.

This research has contributed several insights into the management of sleepiness, indicating that individual sleepiness countermeasures are used regularly, both day-to-day and in shift working city bus drivers. It has highlighted that sugar is believed to be an effective countermeasure by those who use it. Despite this, there is no evidence that glucose can improve reaction time or increase feelings of alertness. For shift working bus drivers, the work environment heavily influences the use, choice, and availability of sleepiness countermeasures, which is a barrier to effective countermeasure use. There are few clear factors which predict which bus drivers will elect to use the possibly ineffective countermeasure of sugar compared to those who elect to use caffeine. With a lack of predictors, it is beneficial for any educational approach aiming to influence this behaviour to be aimed at all drivers. It is vital that drivers are educated in effective strategies to alleviate sleepiness, as part of a wider educational programme focusing on sleep and shift work. Workplaces can support drivers in achieving this by reviewing driver facilities, aiming to reduce workplace barriers. Importantly, for successful engagement, this needs to be delivered in an industry wide open safety culture, including buy in from all stakeholders.