| 1. |
- 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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| 2. |
- Anund, Anna, 1964-, et al.
(författare)
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An on-road study of sleepiness in split shifts among city bus drivers
- 2018
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Ingår i: Accident Analysis and Prevention. - : Elsevier. - 0001-4575 .- 1879-2057. ; 114, s. 71-76
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Tidskriftsartikel (refereegranskat)abstract
- Bus drivers often work irregular hours or split shifts and their work involves high levels of stress. These factors can lead to severe sleepiness and dangerous driving. This study examined how split shift working affects sleepiness and performance during afternoon driving. An experiment was conducted on a real road with a specially equipped regular bus driven by professional bus drivers.The study had a within-subject design and involved 18 professional bus drivers (9 males and 9 females) who drove on two afternoons; one on a day in which they had driven early in the morning (split shift situation) and one on a day when they had been off duty until the test (afternoon shift situation). The hypothesis tested was that split shifts contribute to sleepiness during afternoon, which can increase the safety risks. The overall results supported this hypothesis. In total, five of the 18 drivers reached levels of severe sleepiness (Karolinska Sleepiness Scale ≥8) with an average increase in KSS of 1.94 when driving in the afternoon after working a morning shift compared with being off duty in the morning. This increase corresponded to differences observed between shift workers starting and ending a night shift. The Psychomotor Vigilance Task showed significantly increased response time with split shift working (afternoon: 0.337. s; split shift 0.347. s), as did the EEG-based Karolinska Drowsiness Score mean/max. Blink duration also increased, although the difference was not significant. One driver fell asleep during the drive. In addition, 12 of the 18 bus drivers reported that in their daily work they have to fight to stay awake while driving at least 2-4 times per month. While there were strong individual differences, the study clearly showed that shift-working bus drivers struggle to stay awake and thus countermeasures are needed in order to guarantee safe driving with split shift schedules.
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| 3. |
- Anund, Anna, 1964-, et al.
(författare)
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Bussförares arbetstider kopplat till trötthet
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Bussförare i kollektivtrafiken har ofta oregelbundna arbetstider och en arbetssituation som kan innebära hög stress. Dessa faktorer kan leda till allvarlig trötthet. Syftet med denna studie är att belysa hur arbetstiden påverkar sömn, stress, trötthet och körförmåga. Projektet omfattar fyra delstudier: enkätstudie, sömndagböcker och aktigrafi, analys av schemaläggning och ett experiment på riktig väg med bussförare. Hypoteserna var att tidiga morgonturer, delade skift, långa arbetsdagar och få timmars vila mellan arbetspassen bidrar till trötthet, stress och nedsatt körförmåga, som tillsammans kan leda till en sämre säkerhet. De övergripande resultaten stödjer dessa hypoteser. Generellt sett upplevs sömnighet och trötthet under körning som ett problem eftersom förarna anser att detta innebär nedsatt körförmåga, vilket ökar risken för incidenter och olyckor. Totalt 45 procent av förarna hade minst två gånger i månaden svårt att hålla sig vakna när de kör buss och 19 procent hade under det senaste decenniet varit inblandade i en incident där trötthet varit en bidragande orsak. Experimentet med delade skift med tidig start på morgonen stöder dessa rön. Rapporten avslutas med en lista med förslag.
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| 4. |
- Anund, Anna, 1964-, et al.
(författare)
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Countermeasures for fatigue in transportation : a review of existing methods for drivers on road, rail, sea and in aviation
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim with this study was to gather knowledge about countermeasures for driver fatigue (including sleepiness) in road, rail, sea and air transportation. The knowledge has been used as an input for evaluating advantages and disadvantages with different countermeasures and to estimate their potential to be used regardless mode of transportation. The method used was a literature review and a workshop with experts from all transportation modes. At the workshop the effectiveness of countermeasures for a single mode, but also regardless mode were discussed and a ranking was done. The report discuss the potential of fighting fatigue among drivers for specific mode of transport but also from a more generic point of view, considering scheduling, model prediction of fatigue risk, legislation, a just culture, technical solutions, infrastructure, education, self-administered alertness interventions and fatigue risk management (FRM). The overall judgement was that a just culture, education, possibility to nap and schedules taking the humans limitations into consideration as the most effective countermeasures to fight fatigue, regardless mode of transportation.
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| 5. |
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| 6. |
- Anund, Anna, et al.
(författare)
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Factors associated with self-reported driver sleepiness and incidents in city bus drivers
- 2016
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Ingår i: Industrial Health. - : National Institute of Occupational Safety and Health. - 0019-8366 .- 1880-8026. ; 54:4, s. 337-346
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Tidskriftsartikel (refereegranskat)abstract
- Driver fatigue has received increased attention during recent years and is now considered to be a major contributor to approximately 15-30% of all crashes. However, little is known about fatigue in city bus drivers. It is hypothesized that city bus drivers suffer from sleepiness, which is due to a combination of working conditions, lack of health and reduced sleep quantity and quality.The overall aim with the current study is to investigate if severe driver sleepiness, as indicated by subjective reports of having to fight sleep while driving, is a problem for city based bus drivers in Sweden and if so, to identify the determinants related to working conditions, health and sleep which contribute towards this. The results indicate that driver sleepiness is a problem for city bus drivers, with 19% having to fight to stay awake while driving the bus 2-3 times each week or more and nearly half experiencing this at least 2-4 times per month. In conclusion, severe sleepiness, as indicated by having to fight sleep during driving, was common among the city bus drivers. Severe sleepiness correlated with fatigue related safety risks, such as near crashes.
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| 7. |
- 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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| 8. |
- Filtness, Ashleigh J, et al.
(författare)
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Sleep-related eye symptoms and their potential for identifying driver sleepiness
- 2014
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Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 23:5, s. 568-75
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Tidskriftsartikel (refereegranskat)abstract
- The majority of individuals appear to have insight into their own sleepiness, but there is some evidence that this does not hold true for all, for example treated patients with obstructive sleep apnea. Identification of sleep-related symptoms may help drivers determine their sleepiness, eye symptoms in particular show promise. Sixteen participants completed four motorway drives on two separate occasions. Drives were completed during daytime and night-time in both a driving simulator and on the real road.Ten eye symptoms were rated at the end of each drive, and compared with driving performance and subjective and objective sleep metrics recorded during driving. 'Eye strain', 'difficulty focusing', 'heavy eyelids' and 'difficulty keeping the eyes open' were identified as the four key sleep-related eye symptoms. Drives resulting in these eye symptoms were more likely to have high subjective sleepiness and more line crossings than drives where similar eye discomfort was not reported. Furthermore, drivers having unintentional line crossings were likely to have 'heavy eyelids' and 'difficulty keeping the eyes open'. Results suggest that drivers struggling to identify sleepiness could be assisted with the advice 'stop driving if you feel sleepy and/or have heavy eyelids or difficulty keeping your eyes open'.
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| 9. |
- Hallvig, David, et al.
(författare)
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Real driving at night - predicting lane departures from physiological and subjective sleepiness
- 2014
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Ingår i: Biological Psychology. - : Elsevier BV. - 0301-0511 .- 1873-6246. ; 101, s. 18-23
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Tidskriftsartikel (refereegranskat)abstract
- Only limited information is available on how driving performance relates to physiological and subjective sleepiness on real roads. This relation was the focus of the present study. 33 volunteers drove for 90min on a rural road during the afternoon and night in an instrumented car, while electroencephalography and electrooculography and lane departures were recorded continuously and subjective ratings of sleepiness were made every 5min (Karolinska Sleepiness Scale - KSS). Data was analyzed using Bayesian multilevel modeling. Unintentional LDs increased during night driving, as did KSS and long blink durations(LBD). Lateral position moved to the left . LDs were predicted by self-reported sleepiness and LBDs across time and were significantly higher in individuals with high sleepiness. Removal of intentional LDs, enhanced the KSS/LD relation. It was concluded that LDs, KSS, and LBDs are strongly increased during night driving and that KSS predicts LDs.
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| 10. |
- Hallvig, D., et al.
(författare)
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Sleepy driving on the real road and in the simulator - A comparison
- 2013
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Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575 .- 1879-2057. ; 50, s. 44-50
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Tidskriftsartikel (refereegranskat)abstract
- Sleepiness has been identified as one of the most important factors contributing to road crashes. However, almost all work on the detailed changes in behavior and physiology leading up to sleep related crashes has been carried out in driving simulators. It is not clear, however, to what extent simulator results can be generalized to real driving. This study compared real driving with driving in a high fidelity, moving base, driving simulator with respect to driving performance, sleep related physiology (using electroencephalography and electrooculography) and subjective sleepiness during night and day driving for 10 participants. The real road was emulated in the simulator. The results show that the simulator was associated with higher levels of subjective and physiological sleepiness than real driving. However, both for real and simulated driving, the response to night driving appears to be rather similar for subjective sleepiness and sleep physiology. Lateral variability was more responsive to night driving in the simulator, while real driving at night involved a movement to the left in the lane and a reduction of speed, both of which effects were absent in the simulator. It was concluded that the relative validity of simulators is acceptable for many variables, but that in absolute terms simulators cause higher sleepiness levels than real driving. Thus, generalizations from simulators to real driving must be made with great caution.
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