| 1. |
- Anund, Anna, et al.
(författare)
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The effects of driving situation on sleepiness indicators after sleep loss : A driving simulator study
- 2009
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Ingår i: Industrial Health. - : National Institute of Industrial Health. - 0019-8366 .- 1880-8026. ; 47:4, s. 393-401
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Tidskriftsartikel (refereegranskat)abstract
- Almost all studies of sleepy driving are carried out in driving simulators and with monotonous road conditions (no interaction with other cars). The present study investigated indicators of sleepy driving in a more challenging scenario after a night awake. 17 participants drove a high fidelity moving base driving simulator experiment while sleepiness was monitored physiologically and behaviourally. Short periods of situations of free driving (no other vehicles) alternated with short periods of following another vehicle (car following) with and without the possibility to overtake. The result showed that a night of prior sleep loss increased sleepiness levels at the wheel (eye closure duration and lateral variability) compared to after a night of normal sleep. Blink duration while overtaking was significantly lower compared to the other situations, it was at the same level as after night sleep. Speed when passing a stopped school bus was not significantly affected by sleepiness. However the warning caused a more rapid reduction of speed. In conclusion, a moderately challenging driving contest did not affect sleepiness indicators, but a very challenging one did so (overtaking). This suggests that it is important to monitor the driving situation in field operational tests of sleepy driving.
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| 2. |
- Selander, Helena, 1975-, et al.
(författare)
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Older drivers: On-road and off-road test results
- 2011
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Ingår i: Accident Analysis and Prevention. - : Elsevier Science B.V., Amsterdam.. - 0001-4575 .- 1879-2057. ; 43:4, s. 1348-1354
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Tidskriftsartikel (refereegranskat)abstract
- Eighty-five volunteer drivers, 65-85 years old, without cognitive impairments impacting on their driving were examined, in order to investigate driving errors characteristic for older drivers. In addition, any relationships between cognitive off-road and on-road tests results, the latter being the gold standard, were identified. Performance measurements included Trail Making Test (TMT), Nordic Stroke Driver Screening Assessment (NorSDSA), Useful Field of View (UFOV), self-rating driving performance and the two on-road protocols P-Drive and ROA. Some of the older drivers displayed questionable driving behaviour. In total, 21% of the participants failed the on-road assessment. Some of the specific errors were more serious than others. The most common driving errors embraced speed: exceeding the speed limit or not controlling the speed. Correlations with the P-Drive protocol were established for NorSDSA total score (weak), UFOV subtest 2 (weak), and UFOV subtest 3 (moderate). Correlations with the ROA protocol were established for UFOV subtest 2 (weak) and UFOV subtest 3 (weak). P-Drive and self ratings correlated weakly, whereas no correlation between self ratings and the ROA protocol was found. The results suggest that specific problems or errors seen in an older persons driving can actually be "normal driving behaviours".
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| 3. |
- Ahlström, Christer, 1977-, et al.
(författare)
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Effects of the road environment on the development of driver sleepiness in young male drivers
- 2018
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Ingår i: Accident Analysis and Prevention. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0001-4575 .- 1879-2057. ; 112, s. 127-134
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Tidskriftsartikel (refereegranskat)abstract
- Latent driver sleepiness may in some cases be masked by for example social interaction, stress and physical activity. This short-term modulation of sleepiness may also result from environmental factors, such as when driving in stimulating environments. The aim of this study is to compare two road environments and investigate how they affect driver sleepiness. Thirty young male drivers participated in a driving simulator experiment where they drove two scenarios: a rural environment with winding roads and low traffic density, and a suburban road with higher traffic density and a more built-up roadside environment. The driving task was essentially the same in both scenarios, i.e. to stay on the road, without much interaction with other road users. A 2 x 2 design, with the conditions rural versus suburban, and daytime (full sleep) versus night-time (sleep deprived), was used. The results show that there were only minor effects of the road environment on subjective and physiological indicators of sleepiness. In contrast, there was an increase in subjective sleepiness, longer blink durations and increased EEG alpha content, both due to time on task and to night-time driving. The two road environments differed both in terms of the demand on driver action and of visual load, and the results indicate that action demand is the more important of the two factors. The notion that driver fatigue should be countered in a more stimulating visual environment such as in the city is thus more likely due to increased task demand rather than to a richer visual scenery. This should be investigated in further studies.
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| 4. |
- Nyberg, Jonna, 1967-, et al.
(författare)
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How does driving license withdrawal affect subjective well-being? A Swedish comparative survey study of visual field loss
- 2021
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Ingår i: European Transport Research Review. - : Springer. - 1867-0717 .- 1866-8887. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Research has found strong relationships between access to transport, accessibility of activities, and subjective well-being (SWB), and society is said to be car dependent. Accordingly, this study investigates, in a Swedish context, whether and how withdrawal of a driving license for a private car due to visual field loss (VFL) affects SWB. A web survey was used for statistical comparisons of three respondent groups (n = 436): people with a driving license, people with a driving license and VFL, and people whose driving license was withdrawn due to VFL. The inclusion criterion for all participants was that they should have a diagnosis that could cause VFL. The no-license group had lower overall SWB than did respondents with driving licenses. The no-license group also perceived less access to transport means in order to live a life to be satisfied with than did the other groups. The most used transport means in the no-license group was getting a lift in a car, though this group had a strong desire to drive a car. Few respondents in the license groups wanted to use specific transport means to a greater extent, car driving being the most used transport means. Some inter-group differences were seen regarding how access to activities (measured by frequency of actual trips) affected SWB. This study found a significant negative effect of driving license withdrawal on SWB. However, the results imply that qualitative aspects other than the relationship between the frequencies of trips and activities might also affect SWB, and more research on this subject is needed.
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| 5. |
- Ahlström, Christer, et al.
(författare)
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Fit-for-duty test for estimation of drivers sleepiness level: Eye movements improve the sleep/wake predictor
- 2013
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Ingår i: Transportation Research Part C. - : Elsevier. - 0968-090X .- 1879-2359. ; 26, s. 20-32
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Tidskriftsartikel (refereegranskat)abstract
- Driver sleepiness contributes to a considerable proportion of road accidents, and a fit-for-duty test able to measure a drivers sleepiness level might improve traffic safety. The aim of this study was to develop a fit-for-duty test based on eye movement measurements and on the sleep/wake predictor model (SWP, which predicts the sleepiness level) and evaluate the ability to predict severe sleepiness during real road driving. Twenty-four drivers participated in an experimental study which took place partly in the laboratory, where the fit-for-duty data were acquired, and partly on the road, where the drivers sleepiness was assessed. A series of four measurements were conducted over a 24-h period during different stages of sleepiness. Two separate analyses were performed; a variance analysis and a feature selection followed by classification analysis. In the first analysis it was found that the SWP and several eye movement features involving anti-saccades, pro-saccades, smooth pursuit, pupillometry and fixation stability varied significantly with different stages of sleep deprivation. In the second analysis, a feature set was determined based on floating forward selection. The correlation coefficient between a linear combination of the acquired features and subjective sleepiness (Karolinska sleepiness scale, KSS) was found to be R = 0.73 and the correct classification rate of drivers who reached high levels of sleepiness (KSS andgt;= 8) in the subsequent driving session was 82.4% (sensitivity = 80.0%, specificity = 84.2% and AUC = 0.86). Future improvements of a fit-for-duty test should focus on how to account for individual differences and situational/contextual factors in the test, and whether it is possible to maintain high sensitive/specificity with a shorter test that can be used in a real-life environment, e.g. on professional drivers.
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| 6. |
- Ahlström, Christer, 1977-, et al.
(författare)
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The effect of daylight versus darkness on driver sleepiness : A driving simulator study
- 2017
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Ingår i: Journal of Sleep Research. - : Wiley-Blackwell Publishing Inc.. - 0962-1105 .- 1365-2869.
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Tidskriftsartikel (refereegranskat)abstract
- Driver sleepiness studies are often carried out with alert drivers during daytime and sleep-deprived drivers during night-time. This design results in a mixture of different factors (e.g. circadian effects, homeostatic effects, light conditions) that may confound the results. The aim of this study was to investigate the effect of light conditions on driver sleepiness. Thirty young male drivers (23.6 ± 1.7 years old) participated in a driving simulator experiment where they drove on a rural road. A 2 × 2 design was used with the conditions daylight versus darkness, and daytime (full sleep) versus night-time (sleep deprived). The results show that light condition had an independent effect on the sleepiness variables. The subjective sleepiness measured by Karolinska Sleepiness Scale was higher, lateral position more left-oriented, speed lower, electroencephalogram alpha and theta higher, and blink durations were longer during darkness. The number of line crossings did not change significantly with light condition. The day/night condition had profound effects on most sleepiness indicators while controlling for light condition. The number of line crossings was higher during night driving, Karolinska Sleepiness Scale was higher, blink durations were longer and speed was lower. There were no significant interactions, indicating that light conditions have an additive effect on sleepiness. In conclusion, Karolinska Sleepiness Scale and blink durations increase primarily with sleep deprivation, but also as an effect of darkness. Line crossings are mainly driven by the need for sleep and the reduced alertness at the circadian nadir. Lane position is, however, more determined by light conditions than by sleepiness.
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| 7. |
- Ahlström, Christer, 1977-, et al.
(författare)
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The impact of driver sleepiness on fixation-related brain potentials
- 2020
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Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 29:5
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Tidskriftsartikel (refereegranskat)abstract
- The effects of driver sleepiness are often quantified as deteriorated driving performance, increased blink durations and high levels of subjective sleepiness. Driver sleepiness has also been associated with increasing levels of electroencephalogram (EEG) power, especially in the alpha range. The present exploratory study investigated a new measure of driver sleepiness, the EEG fixation-related lambda response. Thirty young male drivers (23.6 +/- 1.7 years old) participated in a driving simulator experiment in which they drove on rural and suburban roads in simulated daylight versus darkness during both the daytime (full sleep) and night-time (sleep deprived). The results show lower lambda responses during night driving and with longer time on task, indicating that sleep deprivation and time on task cause a general decrement in cortical responsiveness to incoming visual stimuli. Levels of subjective sleepiness and line crossings were higher under the same conditions. Furthermore, results of a linear mixed-effects model showed that low lambda responses are associated with high subjective sleepiness and more line crossings. We suggest that the fixation-related lambda response can be used to investigate driving impairment induced by sleep deprivation while driving and that, after further refinement, it may be useful as an objective measure of driver sleepiness.
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| 8. |
- Anund, Anna, 1964-, et al.
(författare)
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Are professional drivers less sleepy than non-professional drivers?
- 2018
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Ingår i: Scandinavian Journal of Work, Environment and Health. - : SCANDINAVIAN JOURNAL WORK ENVIRONMENT & HEALTH. - 0355-3140 .- 1795-990X. ; 44:1, s. 88-95
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Tidskriftsartikel (refereegranskat)abstract
- Objective It is generally believed that professional drivers can manage quite severe fatigue before routine driving performance is affected. In addition, there are results indicating that professional drivers can adapt to prolonged night shifts and may be able to learn to drive without decreased performance under high levels of sleepiness. However, very little research has been conducted to compare professionals and non-professionals when controlling for time driven and time of day.Method The aim of this study was to use a driving simulator to investigate whether professional drivers are more resistant to sleep deprivation than non-professional drivers. Differences in the development of sleepiness (self-reported, physiological and behavioral) during driving was investigated in 11 young professional and 15 non-professional drivers.Results Professional drivers self-reported significantly lower sleepiness while driving a simulator than nonprofessional drivers. In contradiction, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness. They also drove faster. The reason for the discrepancy in the relation between the different sleepiness indicators for the two groups could be due to more experience to sleepiness among the professional drivers or possibly to the faster speed, which might unconsciously have been used by the professionals to try to counteract sleepiness.Conclusion Professional drivers self-reported significantly lower sleepiness while driving a simulator than non-professional drivers. However, they showed longer blink durations and more line crossings, both of which are indicators of sleepiness, and they drove faster.
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| 9. |
- Anund, Anna, et al.
(författare)
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Observer Rated Sleepiness and Real Road Driving : An Explorative Study
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:5, s. e64782-
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to explore if observer rated sleepiness (ORS) is a feasible method for quantification of driver sleepiness in field studies. Two measures of ORS were used:one for behavioural signs based on facial expression, body gestures and body movements labelled B-ORS, andone based on driving performance e.g. if swerving and other indicators of impaired driving occurs, labelled D-ORSA limited number of observers sitting in the back of an experimental vehicle on a motorway about 2 hours repeatedly 3 times per day (before lunch, after lunch, at night) observed 24 participant's sleepiness level with help of the two observer scales. At the same time the participant reported subjective sleepiness (KSS), EOG was recorded (for calculation of blink duration) and several driving measure were taken and synchronized with the reporting.Based on mixed model Anova and correlation analysis the result showed that observer ratings of sleepiness based on drivers' impaired performance and behavioural signs are sensitive to extend the general pattern of time awake, circadian phase and time of driving. The detailed analysis of the subjective sleepiness and ORS showed weak correspondence on an individual level. Only 16% of the changes in KSS were predicted by the observer. The correlation between the observer ratings based on performance (D-ORS) and behavioural signs (B-ORS) are high (r =. 588), and the B-ORS shows a moderately strong association (r =. 360) with blink duration. Both ORS measures show an association (r>0.45) with KSS, whereas the association with driving performance is weak.The results show that the ORS-method detects the expected general variations in sleepy driving in field studies, however, sudden changes in driver sleepiness on a detailed level as 5 minutes is usually not detected; this holds true both when taking into account driving behaviour or driver behavioural signs.
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| 10. |
- Fredin-Knutzén, Johan, et al.
(författare)
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Train drivers' work-related stress and job satisfaction
- 2023
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Ingår i: Journal of Occupational and Environmental Medicine. - : Lippincott Williams & Wilkins. - 1076-2752 .- 1536-5948. ; 65:9, s. 775-782
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: This study investigated which work-related stressors are rated highest by train drivers and which are strongest correlated with consideration to change profession.Methods: In a questionnaire, a total of 251 Swedish train drivers rated 17 work-related stressors, to which extent they had considered quitting their profession, and if they had experienced a PUT (person under train) accident.Results: PUTs (when experienced) and irregular work hours are the main stressors, but the strongest predictors of consideration to change profession are those that are encountered often, and last over time (eg, irregular work hours, r = 0.61, and major organizational changes, r = 0.51).Conclusions: For effective reduction of stress and improved job satisfaction, focus should be on aspects that affect everyday life for drivers, such as better working shifts, less delays, and improved social climate.
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