Subjective and predicted sleepiness while driving in young adults

Identifying Interactive Factors That May Increase Crash Risk between Young Drivers and Trucks: A Narrative Review

Sharing the road with trucks is associated with increased risk of serious injury and death for passenger vehicle drivers. However, the onus for minimising risk lies not just with truck drivers; other drivers must understand the unique performance limitations of trucks associated with stopping distances, blind spots, and turning manoeuverability, so they can suitably act and react around trucks. Given the paucity of research aimed at understanding the specific crash risk vulnerability of young drivers around trucks, the authors employ a narrative review methodology that brings together evidence from both truck and young driver road safety research domains, as well as data regarding known crash risks for each driving cohort, to gain a comprehensive understanding of what young drivers are likely to know about heavy vehicle performance limitations, where there may be gaps in their understanding, and how this could potentially increase crash risk. We then review literature regarding the human factors affecting young drivers to understand how perceptual immaturity and engagement in risky driving behaviours are likely to compound risk regarding both the frequency and severity of collision between trucks and young drivers. Finally, we review current targeted educational initiatives and suggest that simply raising awareness of truck limitations is insufficient. We propose that further research is needed to ensure initiatives aimed at increasing young driver awareness of trucks and truck safety are evidence-based, undergo rigorous evaluation, and are delivered in a way that aims to (i) increase young driver risk perception skills, and (ii) reduce risky driving behaviour around trucks.

Graph analysis of functional brain network topology using minimum spanning tree in driver drowsiness

A large number of traffic accidents due to driver drowsiness have been under more attention of many countries. The organization of the functional brain network is associated with drowsiness, but little is known about the brain network topology that is modulated by drowsiness. To clarify this problem, in this study, we introduce a novel approach to detect driver drowsiness. Electroencephalogram (EEG) signals have been measured during a simulated driving task, in which participants are recruited to undergo both alert and drowsy states. The filtered EEG signals are then decomposed into multiple frequency bands by wavelet packet transform. Functional connectivity between all pairs of channels for multiple frequency bands is assessed using the phase lag index (PLI). Based on this, PLI-weighted networks are subsequently calculated, from which minimum spanning trees are constructed-a graph method that corrects for comparison bias. Statistical analyses are performed on graph-derived metrics as well as on the PLI connectivity values. The major finding is that significant differences in the delta frequency band for three graph metrics and in the theta frequency band for five graph metrics suggesting network integration and communication between network nodes are increased from alertness to drowsiness. Together, our findings also suggest a more line-like configuration in alert states and a more star-like topology in drowsy states. Collectively, our findings point to a more proficient configuration in drowsy state for lower frequency bands. Graph metrics relate to the intrinsic organization of functional brain networks, and these graph metrics may provide additional insights on driver drowsiness detection for reducing and preventing traffic accidents and further understanding the neural mechanisms of driver drowsiness.

Motivational factors associated with drowsy driving behavior: a qualitative investigation of college students

OBJECTIVES

This qualitative investigation sought to identify the motivational factors that contribute to drowsy driving in college students and to discover important messaging strategies that may help prevent or reduce this behavior in this population.

DESIGN

Four focus groups of college students.

SETTING

A large university in the Washington, DC, metropolitan area during the Fall 2016 term.

PARTICIPANTS

Twenty-six undergraduate students between the ages of 18 and 25 years.

MEASUREMENTS

Notes and transcripts from the focus group sessions were analyzed to identify recurring themes regarding attitudes, motivations, experiences, influences, and potential preventive messaging strategies related to drowsy driving.

RESULTS

Although most participants had heard of drowsy driving and were concerned about it, they did not associate it with legal risks and were more concerned about alcohol-impaired and distracted driving as crash risks. Participants viewed drowsy driving as a normal and unavoidable part of their lives over which they had little control. For potential anti-drowsy driving messaging strategies, participants preferred messages delivered via audiovisual or social media that featured graphic and emotional portrayals of crashes and their consequences. Participants also voiced strong support for preventive messaging strategies equating various degrees of sleep deprivation to known impairing levels of alcohol, as well as messages providing cues to action to actual drowsy drivers on roadways.

CONCLUSIONS

Increased enforcement, education, and public messaging campaigns are needed to increase knowledge and influence attitudes and opinions among young drivers about the dangers and social unacceptability of drowsy driving.

Asleep at the Wheel-The Road to Addressing Drowsy Driving

Drowsy driving is a dangerous behavior that leads to thousands of deaths and injuries each year. It is also a controllable factor for drivers. Drivers are capable of modifying this behavior if given sufficient information and motivation. Our goal is to establish a comprehensive and strategic effort to end drowsy driving crashes and deaths. This article highlights some of the conclusions of a unique recent meeting of sleep experts and highway safety professionals and describes the first steps the community has taken and plans to take in the future to address this issue.

Sleepiness while driving and shiftwork patterns among Korean bus drivers

BACKGROUND

Sleepiness while driving has been regarded as a major cause of death due to traffic accidents. We compared the degree of sleepiness across five different working time periods (first, morning, post-lunch, afternoon, and last) among Korean bus drivers with different shift types (Daily two shift/Alternating day shift).

METHOD

We interviewed 332 bus drivers with two shift types (Daily two shift, 128; Alternating day shift, 204). The questionnaire included demographic information (age, alcohol consumption and history of disease), a sleep disorder diagnosed by a doctor, job duration, the number of workdays in the past month, average working hours per workday and week, sleepiness while driving (Karolinska Sleepiness Scale), and sleeping time for both workdays and off-days. We conducted log-binomial regression analyses and produced prevalence ratios (PRs) of severe sleepiness (KSS ≥ 7) while driving with 95% confidence intervals (95% CI) to identify the difference in sleepiness for five working times between both groups.

RESULTS

For the first and morning periods, there were no statistically significant differences in the KSS scores between the two groups. However, from lunch to last driving, drivers with Alternating day shift had a much larger proportion of severe sleepiness than those on Daily two shift. Thirteen (10.2%), 2 (1.6%) and 7 (5.5%) Daily two shift workers reported severe sleepiness in the post-lunch, afternoon and last periods. In contrast, 81 (39.7%), 63 (30.9%) and 64 (31.4%) of Alternating day shift drivers experienced severe sleepiness during the post-lunch, afternoon and last driving periods (p < 0.0001). According to the log-binomial regression analyses, Alternating day shift was associated with severe sleepiness from lunch to last driving. After adjusting for job duration, alcohol consumption and sleeping time on workdays, the PRs were 3.97 (95% CI: 2.29-6.90) post-lunch, 18.26 (95% CI: 4.51-73.89) in the afternoon and 5.71 (95% CI: 2.51-12.99) for the last driving period.

CONCLUSION

We found that Alternating day shift bus drivers suffered from more sleepiness while driving from lunch to last driving than Daily two shift bus drivers. This difference may be because Alternating day shift drivers had more irregular work schedules and longer working hours per day and week.

Generalizability of Frequency Weighting Curve for Extraction of Spectral Drowsy Component From the EEG Signals Recorded in Eyes-Closed Condition

One of the critical barriers to reducing the threats of sleep loss to public health, safety, and productivity is a lack of practical tools for quick identification of objective level of sleepiness. We examined a novel sleepiness measure named "spectral drowsy component score" to provide evidence for generalizability of a frequency weighting curve required for calculation of this measure. Each spectral drowsy component score is a sum of 16 weighted ln-transformed single-Hz power densities (1-16 Hz) obtained by the fast Fourier transformation of an electroencephalographic signal recorded during the first minute after closing the eyes. A set of 16 weights (frequency weighting curve) is derived empirically. One type of such curve is a correlation spectrum. It consists of 16 coefficients of correlation of a group-averaged experimental time course of sleepiness with16 time courses of single-Hz power densities. Sleepiness is determined either subjectively (by self-scoring on the Karolinska Sleepiness Scale) or objectively (as sleep latency). Another type is a differential spectrum reflecting difference between 2 sets of 16 power densities obtained for either distant phases of sleep deprivation experiment or distinct alertness-sleepiness substates. Analysis of 3 datasets collected in sleep deprivation experiments with, in total, 160 participants showed that, despite differences in the protocols of these experiments and ages of their participants, the forms of frequency weighting curves always resembled one another. Such resemblance led to practical identity of scoring results. We concluded that spectral drowsy component scoring might be implemented into quick, simple, direct, transparent, and objective test of sleepiness.

Predicting drowsy driving in real-time situations: Using an advanced driving simulator, accelerated failure time model, and virtual location-based services

This paper aims to both identify the factors affecting driver drowsiness and to develop a real-time drowsy driving probability model based on virtual Location-Based Services (LBS) data obtained using a driving simulator. A driving simulation experiment was designed and conducted using 32 participant drivers. Collected data included the continuous driving time before detection of drowsiness and virtual LBS data related to temperature, time of day, lane width, average travel speed, driving time in heavy traffic, and driving time on different roadway types. Demographic information, such as nap habit, age, gender, and driving experience was also collected through questionnaires distributed to the participants. An Accelerated Failure Time (AFT) model was developed to estimate the driving time before detection of drowsiness. The results of the AFT model showed driving time before drowsiness was longer during the day than at night, and was longer at lower temperatures. Additionally, drivers who identified as having a nap habit were more vulnerable to drowsiness. Generally, higher average travel speeds were correlated to a higher risk of drowsy driving, as were longer periods of low-speed driving in traffic jam conditions. Considering different road types, drivers felt drowsy more quickly on freeways compared to other facilities. The proposed model provides a better understanding of how driver drowsiness is influenced by different environmental and demographic factors. The model can be used to provide real-time data for the LBS-based drowsy driving warning system, improving past methods based only on a fixed driving.

Traffic accidents involving fatigue driving and their extent of casualties

The rapid progress of motorization has increased the number of traffic-related casualties. Although fatigue driving is a major cause of traffic accidents, the public remains not rather aware of its potential harmfulness. Fatigue driving has been termed as a "silent killer." Thus, a thorough study of traffic accidents and the risk factors associated with fatigue-related casualties is of utmost importance. In this study, we analyze traffic accident data for the period 2006-2010 in Guangdong Province, China. The study data were extracted from the traffic accident database of China's Public Security Department. A logistic regression model is used to assess the effect of driver characteristics, type of vehicles, road conditions, and environmental factors on fatigue-related traffic accident occurrence and severity. On the one hand, male drivers, trucks, driving during midnight to dawn, and morning rush hours are identified as risk factors of fatigue-related crashes but do not necessarily result in severe casualties. Driving at night without street-lights contributes to fatigue-related crashes and severe casualties. On the other hand, while factors such as less experienced drivers, unsafe vehicle status, slippery roads, driving at night with street-lights, and weekends do not have significant effect on fatigue-related crashes, yet accidents associated with these factors are likely to have severe casualties. The empirical results of the present study have important policy implications on the reduction of fatigue-related crashes as well as their severity.

Continuing to drive while sleepy: the influence of sleepiness countermeasures, motivation for driving sleepy, and risk perception

Driver sleepiness is a major contributor to road crashes. The current study sought to examine the association between perceptions of effectiveness of six sleepiness countermeasures and their relationship with self-reports of continuing to drive while sleepy among 309 drivers after controlling for the influence of age, sex, motivation for driving sleepy, and risk perception of sleepy driving. The results demonstrate that the variables of age, sex, motivation, and risk perception were significantly associated with self-reports of continuing to drive while sleepy and only one countermeasure was associated with self-reports of continuing to drive while sleepy. Further, it was found that age differences in self-reports of continuing to drive while sleepy was mediated by participants' motivation and risk perception. These findings highlight modifiable factors that could be focused on with interventions that seek to modify drivers' attitudes and behaviours of driving while sleepy.

"I drove after drinking alcohol" and other risky driving behaviours reported by young novice drivers

BACKGROUND

Volitional risky driving behaviours such as drink- and drug-driving (i.e. substance-impaired driving) and speeding contribute to the overrepresentation of young novice drivers in road crash fatalities, and crash risk is greatest during the first year of independent driving in particular.

AIMS

To explore the: (1) self-reported compliance of drivers with road rules regarding substance-impaired driving and other risky driving behaviours (e.g., speeding, driving while tired), one year after progression from a Learner to a Provisional (intermediate) licence; and (2) interrelationships between substance-impaired driving and other risky driving behaviours (e.g., crashes, offences, and Police avoidance).

METHODS

Drivers (n=1076; 319 males) aged 18-20 years were surveyed regarding their sociodemographics (age, gender) and self-reported driving behaviours including crashes, offences, Police avoidance, and driving intentions.

RESULTS

A relatively small proportion of participants reported driving after taking drugs (6.3% of males, 1.3% of females) and drinking alcohol (18.5% of males, 11.8% of females). In comparison, a considerable proportion of participants reported at least occasionally exceeding speed limits (86.7% of novices), and risky behaviours like driving when tired (83.6% of novices). Substance-impaired driving was associated with avoiding Police, speeding, risky driving intentions, and self-reported crashes and offences. Forty-three percent of respondents who drove after taking drugs also reported alcohol-impaired driving.

DISCUSSION AND CONCLUSIONS

Behaviours of concern include drink driving, speeding, novice driving errors such as misjudging the speed of oncoming vehicles, violations of graduated driver licensing passenger restrictions, driving tired, driving faster if in a bad mood, and active punishment avoidance. Given the interrelationships between the risky driving behaviours, a deeper understanding of influential factors is required to inform targeted and general countermeasure implementation and evaluation during this critical driving period. Notwithstanding this, a combination of enforcement, education, and engineering efforts appear necessary to improve the road safety of the young novice driver, and for the drink-driving young novice driver in particular.

Re-conceptualising the reckless driving behaviour of young drivers

Reckless driving is a major contributing factor to road morbidity and mortality. While further research into the nature and impact of reckless driving, particularly among young people, is urgently needed, the measurement of reckless driving behaviour also requires increased attention. Three major shortcomings apparent in established measures of driver behaviour are that they do not target the full range of reckless driving behaviours, they measure characteristics other than driving behaviours, and/or they fail to categorise and label reckless driver behaviour based on characteristics of the behaviours themselves. To combat these shortcomings, this paper reports the development and preliminary validation of a new measure of reckless driving behaviour for young drivers. Exploratory factor analysis of self-reported driving data revealed four, conceptually distinct categories of reckless driving behaviour: those that increase crash-risk due to (a) distractions or deficits in perception, attention or reaction time (labelled "distracted"), (b) driving under the influence of drugs or alcohol (labelled "substance-use"), (c) placing the vehicle in an unsafe environment beyond its design expectations (labelled "extreme"), and (d) speed and positioning of the vehicle relative to other vehicles and objects (labelled "positioning"). Confirmatory factor analysis of data collected from a separate, community sample confirmed this four-factor structure. Multiple regression analyses found differences in the demographic and psychological variables related to these four factors, suggesting that interventions in one reckless driving domain may not be helpful in others.

Calibration of an objective alertness scale

In order to establish validity of an objective scale of alertness-sleepiness, one is forced to somehow calibrate it using subjective scales, such as the Karolinska Sleepiness Scale (KSS). We evaluated the effects of prolonged wakefulness on the extent of disagreement between objective and subjective KSS assessments, and tested whether calibration of an objective alertness-sleepiness scale can be established despite the limited reliability of subjective reports. Starting from 7p.m., the resting electroencephalogram (EEG) was recorded at 2-hour intervals over the last 32-50 h of 44-61-hour wakefulness of 15 healthy study participants. Frontal and occipital scores on the 2nd principal component of the EEG spectrum and occipital alpha-theta power difference were computed for 1-min intervals of 5-min eyes-closed EEG recordings. To obtain alertness scale scores in the range from 5 to 0, positive and negative values of these EEG indexes were assigned to 1 and 0, respectively, and then summed. Although correlation between time courses of objective and subjective (KSS) scores was very strong, evidence for systematic errors in both the mean and the calibration was also found. Correction of these errors resulted in strengthening of correlation (r = 0.99) and establishing one-to-one correspondence between the steps of objective and subjective scales. The results indicate that scores from 5 to 0 on the objective alertness scale can be anchored to minimal, mild, moderate, marked, severe, and disabling levels of sleepiness.

Thrill and adventure seeking as a modifier of the relationship of perceived risk with risky driving among young drivers

Risky driving contributes to road trauma, a leading cause of mortality among young people. Health-relevant behaviour models suggest a negative relationship between risky driving and perceived risk of its outcomes. However, high sensation seekers may value the "thrill" of the risk, and positive associations between sensation seeking and risky driving have been observed. This is the first study to examine whether aspects of sensation seeking modify the relationship between perceived risk and risky driving. Young drivers in metropolitan Sydney and rural New South Wales [NSW] (n=797) completed a survey relating to one of the four risky driving behaviours (speeding, drink-driving, driving while fatigued, and failing to wear a seatbelt). Results suggest that the Thrill and Adventure Seeking subscale of Zuckerman's (1994) Sensation Seeking Scale moderate the relationship of perceived risk with risky driving - indicating a negative relationship for low-scores, but not high-scorers, on the TAS subscale. Thus, road safety campaigns that emphasize the riskiness of a particular behaviour may be of limited benefit to thrill and adventure seekers.

Young drivers' perceptions of culpability of sleep-deprived versus drinking drivers

INTRODUCTION

Sleep-deprived driving can be as dangerous as alcohol-impaired driving, however, little is known about attitudes toward sleep-deprived drivers. This study examined the extent to which young drivers regard sleep-deprived compared to drinking drivers as culpable for a crash, and how their perceptions of driving while in these conditions differ.

METHOD

University student participants (N=295; M=20.4years, SD=1.3; 81% women) were randomly assigned to read one of five fatal motor-vehicle crash scenarios, which differed by aspects of the driver's condition. Culpability ratings for the drinking driver were higher than those for the sleep-deprived driver.

RESULTS

Qualitative findings revealed that driving while sleep-deprived was viewed as understandable, and driving after drinking was viewed as definitely wrong. The dangers of sleep-deprived driving remain under-recognized.

Effectiveness of UK motorway services areas in reducing sleep-related and other collisions

In the UK, motorway service areas (MSAs) are believed to be helpful in reducing sleep ('fatigue') related collisions (SRCs), however, their actual effectiveness has yet to be evaluated. During a 2-3-year period, and over two sections of UK motorways comprising 14 MSA sites, assessments were undertaken of all fatal and injury road traffic collisions (RTCs), especially SRCs. Analyses examined whether there was: (i) a reduction in collisions 16 km beyond MSAs compared with the same distance beforehand; (ii) accumulation of collisions with increasing inter-MSA distances. Within the 16 km regions there was a non-significant fall in all RTCs from 355 before MSAs, to 304 afterwards. However, the 22% decrease in SRCs (108 vs. 84) was significant. Cars comprised the greatest reduction in SRCs possibly attributable to a MSA. Including and beyond these 16 km regions, there was no correlation between inter-MSA distances and accumulated RTCs or SRCs (n=682 of which 181 were SRCs [26%]). There were obvious differences between MSAs in all these respects. Of the 23 fatal RTCs, 17 were SRCs. Whilst SRCs had their greatest daily incidence between 02:00 h and 06:00 h, as expected, MSAs seemed to have their least beneficial effect on SRCs during this vulnerable period, which is a matter for concern.

Short sleep duration and long spells of driving are associated with the occurrence of Japanese drivers' rear-end collisions and single-car accidents

Sleepiness and fatigue are important risk factors for traffic accidents. However, the relation between the accident type and lack of sleep as well as spells of driving has not been examined sufficiently. This study aimed to clarify that short sleep duration and long spells of driving are more associated with rear-end collisions and single-car accidents as compared with accidents of other types in cases of people who cause accidents. After removing drunken driving as a cause of accidents, 1772 parties involved in accidents were questioned. The quantities of rear-end collisions and single-car accidents were, respectively, 240 and 293. Logistic regression analysis showed that short nocturnal sleep (<6 h) and 10-min increments of spells of driving were significantly associated not only with rear-end collisions but also with single-car accidents as compared with accidents of other types. Furthermore, younger age (<or=25 years old) and nighttime (21:00-06:00 h) driving were significantly associated with single-car accidents as compared with accidents of other types. To prevent such accidents, countermeasures must be considered in light of the characteristics of drivers involved in each type of accident described above.

Hazard perception in novice and experienced drivers: the effects of sleepiness

One driver skill that has been found to correlate with crash risk is hazard perception ability. The purpose of this study was to investigate how hazard perception latencies change between high and low sleepiness for a high risk group (novice drivers) and a lower risk group (experienced drivers). Thirty-two novice drivers (aged 17-24 years) and 30 experienced drivers (aged 28-36) completed a validated video-based hazard perception test, in which participants were asked to anticipate genuine traffic conflicts in footage filmed from the driver's perspective, with separate groups tested at either 10a.m. (lower sleepiness) or at 3a.m. (higher sleepiness). We found a significant interaction between sleepiness and experience, indicating that the hazard perception skills of the more experienced drivers were relatively unaffected by mild increases in sleepiness while the inexperienced drivers were significantly slowed. The findings suggest that the disproportionate sleepiness-related accident involvement of young, inexperienced drivers could be partly due to a slowing of their ability to anticipate traffic hazards.

Awareness of driving while sleepy and road traffic accidents: prospective study in GAZEL cohort

OBJECTIVES

To examine the association between self assessed driving while sleepy and the risk of serious road traffic accidents (RTAs).

DESIGN

Prospective cohort study.

SETTING

France.

PARTICIPANTS

13 299 of the 19 894 living members of the GAZEL cohort, workers and recent retirees of a French national utility company followed up since 1989.

MAIN OUTCOME MEASURES

Frequency of driving while sleepy in the previous 12 months, reported in 2001; rate ratios for serious RTAs in 2001-3, estimated by using generalised linear Poisson regression models with time dependent covariates.

RESULTS

The risk of serious RTAs increased proportionally with the frequency of self reported driving while sleepy. After adjustment for sociodemographic characteristics, driving behaviour variables, work conditions, retirement, medical conditions and treatments, depressive symptoms, and sleep disorders, the adjusted rate ratios of serious RTAs for participants who reported driving while sleepy in the previous 12 months "a few times" or "once a month or more often" were 1.5 (95% confidence interval 1.2 to 2.0) and 2.9 (1.3 to 6.3) respectively compared with those who reported not driving while sleepy over the same period. These associations were not explained by any reported sleep disorders.

CONCLUSIONS

Self assessed driving while sleepy was a powerful predictor of serious RTAs, suggesting that drivers' awareness of their sleepiness while driving is not sufficient to prevent them from having RTAs. Messages on prevention should therefore focus on convincing sleepy drivers to stop driving and sleep before resuming their journey.

Graduated driver licensing and teenage driver research in 2006

This is the third update of research on graduated driver licensing (GDL) and related teenage driver issues. It briefly summarizes research published since or not included in the 2005 update (Hedlund, J., & Compton, R. (2005). Graduated driver licensing research in 2004 and 2005. Journal of Safety Research, 36(2), 109-119.), describes research in progress of which the authors are aware, and announces plans for a symposium on teenage driving and GDL to be held in February 2007.