1.
Hallvig, D., et al.
(författare)
Sleepy driving on the real road and in the simulator - A comparison
2013
Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575 .- 1879-2057. ; 50, s. 44-50
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.
2.
Filtness, Ashleigh J, et al.
(författare)
Sleep-related eye symptoms and their potential for identifying driver sleepiness
2014
Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 23:5, s. 568-75
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'.
3.
Mårdh, Selina, et al.
(författare)
Driving restrictions post-stroke : Physicians' compliance with regulations
2017
Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-9588 .- 1538-957X. ; , s. 1-4
Tidskriftsartikel (refereegranskat) abstract
Objective: Suffering a stroke might lead to permanent cognitive and/or physical impairment. It has been shown that these impairments could have an impact on an individual's fitness to drive. In Sweden, as in many other countries, there are regulations on driving cessation post-stroke. Information on driving cessation should be given to all patients and noted in the journal.The present study sought to determine physician's compliance to driving regulations post-stroke as well as follow-up and gender aspects.Method: A retrospective study of medical records on stroke patients was carried out. The study covered all of the medical records on stroke incidents (n = 342) during a year at a typical medium to large-sized hospital in Sweden.Results: A journal entry on driving cessation post-stroke was missing in 81% of the medical records. Only 2% of the patients were scheduled for a follow-up meeting specifically concerning fitness to drive. Significantly more men than women had an entry on driving in the journal.Conclusions: We conclude that the Swedish regulations on driving cessation post-stroke were not followed at the participating hospital. It is crucial that all stroke patients receive information on driving cessation because their condition might affect fitness to drive. Analysis of follow-up records showed that there was no consistent method for assessment of a patient's fitness to drive. There was also a gender difference in the material, which warrants further investigation.
4.
Sandberg, David, 1980, et al.
(författare)
The Characteristics of Sleepiness During Real Driving at Night - A Study of Driving Performance, Physiology and Subjective Experience
2011
Ingår i: Sleep. - 1550-9109 .- 0161-8105. ; 34:10, s. 1317-1325
Tidskriftsartikel (refereegranskat) abstract
Study Objectives: Most studies of sleepy driving have been carried out in driving simulators. A few studies of real driving are available, but these have used only a few sleepiness indicators. The purpose of the present study was to characterize sleepiness in several indicators during real driving at night, compared with daytime driving. Design: Participants drove 55 km (at 90km/h) on a 9-m-wide rural highway in southern Sweden. Daytime driving started at 09: 00 or 11: 00 (2 groups) and night driving at 01: 00 or 03: 00 (balanced design). Setting: Instrumented car on a real road in normal traffic. Participants: Eighteen participants drawn from the local driving license register. Interventions: Daytime and nighttime drives. Measurement and Results: The vehicle was an instrumented car with video monitoring of the edge of the road and recording of the lateral position and speed. Electroencephalography and electrooculography were recorded, together with ratings of sleepiness every 5 minutes. Pronounced effects of night driving were seen for subjective sleepiness, electroencephalographic indicators of sleepiness, blink duration, and speed. Also, time on task showed significant effects for subjective sleepiness, blink duration, lane position, and speed. Sleepiness was highest toward the end of the nighttime drive. Night driving caused a leftward shift in lateral position and a reduction of speed. The latter two findings, as well as the overall pattern of sleepiness indicators, provide new insights into the effects of night driving. Conclusion: Night driving is associated with high levels of subjective, electrophysiologic, and behavioral sleepiness.
5.
Sandberg, David, 1980, et al.
(författare)
The impact of sleepiness on lane positioning in truck driving
2013. - 1
Ingår i: Driver Distraction and Inattention. - Farnham : Ashgate. - 9781409425854 - 9781315578156 ; , s. 405-416, s. 405-416
Bokkapitel (refereegranskat) abstract
This chapter concerns the detection of sleepiness in truck drivers. Data obtained from a driver sleepiness study involving real-world driving are used in order to analyse the performance of several sleepiness indicators based on driving behavior; such as, for example, variability in lateral position and heading angle. Contrary to the results obtained for passenger cars, for heavy trucks it is found that indicators based on variability provide little or no information; their performance does not rise significantly above chance levels.However, the data indicate that there is a significant difference in the average lane position for sleepy and alert drivers, respectively, such that a sleepy driver generally places the vehicle closer (by about 0.2 m) to the centre of the road than an alert driver. The analysis also shows a significant, monotonous, increase in average lateral position (measured from the right, outer, lane boundary towards the lane centre) between the four cases of (i) daytime alert driving, (ii) daytime sleepy driving, (iii) night-time alert driving and (iv) nighttime sleepy driving.
6.
7.
Vadeby, Anna, et al.
(författare)
Sleepiness and prediction of driver impairment in simulator studies using a Cox proportional hazard approach
2010
Ingår i: Accident Analysis and Prevention. - : Elsevier BV. - 0001-4575 .- 1879-2057. ; 42:3, s. 835-41
Tidskriftsartikel (refereegranskat) abstract
Cox proportional hazard models were used to study relationships between the event that a driver is leaving the lane caused by sleepiness and different indicators of sleepiness. In order to elucidate different indicators' performance, five different models developed by Cox proportional hazard on a data set from a simulator study were used. The models consisted of physiological indicators and indicators from driving data both as stand alone and in combination. The different models were compared on two different data sets by means of sensitivity and specificity and the models' ability to predict lane departure was studied.In conclusion, a combination of blink indicators based on the ratio between blink amplitude and peak closing velocity of eyelid (A/PCV) (or blink amplitude and peak opening velocity of eyelid (A/POV)), standard deviation of lateral position and standard deviation of lateral acceleration relative road (ddy) was the most sensitive approach with sensitivity 0.80. This is also supported by the fact that driving data only shows the impairment of driving performance while blink data have a closer relation to sleepiness. Thus, an effective sleepiness warning system may be based on a combination of lane variability measures and variables related to eye movements (particularly slow eye closure) in order to have both high sensitivity (many correct warnings) and acceptable specificity (few false alarms).
8.
Åkerstedt, Torbjörn, et al.
(författare)
Having to stop driving at night because of dangerous sleepiness : awareness, physiology and behaviour
2013
Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 22:4, s. 380-388
Tidskriftsartikel (refereegranskat) abstract
A large number of accidents are due to the driver falling asleep at the wheel, but details of this link have not been studied on a real road. The purpose of the present study was to describe the development of sleepiness indicators, leading to the drive being terminated prematurely by the onboard expert driving instructor because of imminent danger. Eighteen individuals participated during a day drive and a night drive on a motorway (both 90 min). Eight drivers terminated (N) prematurely (after 43 min) because of sleep-related imminent danger [according to the driving instructor or their own judgement (two cases)].The results showed very high sleepiness ratings (8.5 units on the Karolinska Sleepiness Scale) immediately before termination (<7 at a similar time interval for those 10 who completed the drive). Group N also showed significantly higher levels of sleep intrusions on the electroencephalography/electro-oculography (EEG/EOG) than those who completed the drive (group C). The sleep intrusions were increased in group N during the first 40 min of the night drive. During the day drive, sleep intrusions were increased significantly in group N. The night drive showed significant increases of all sleepiness indicators compared to the day drive, but also reduced speed and driving to the left in the lane. It was concluded that 44% of drivers during late-night driving became dangerously sleepy, and that this group showed higher perceived sleepiness and more sleep intrusions in the EEG/EOG.
9.
Åkerstedt, Torbjörn, et al.
(författare)
Reaction of sleepiness indicators to partial sleep deprivation, time of day and time on task in a driving simulator - the DROWSI project
2010
Ingår i: Journal of Sleep Research. - : Wiley. - 1365-2869 .- 0962-1105. ; 19:2, s. 298-309
Tidskriftsartikel (refereegranskat) abstract
Studies of driving and sleepiness indicators have mainly focused on prior sleep reduction. The present study sought to identify sleepiness indicators responsive to several potential regulators of sleepiness: sleep loss, time of day (TOD) and time on task (TOT) during simulator driving. Thirteen subjects drove a high-fidelity moving base simulator in six 1-h sessions across a 24-h period, after normal sleep duration (8 h) and after partial sleep deprivation (PSD; 4 h). The results showed clear main effects of TOD (night) and TOT but not for PSD, although the latter strongly interacted with TOD. The most sensitive variable was subjective sleepiness, the standard deviation of lateral position (SDLAT) and measures of eye closure [duration, speed (slow), amplitude (low)]. Measures of electroencephalography and line crossings (LCs) showed only modest responses. For most variables individual differences vastly exceeded those of the fixed effects, except for subjective sleepiness and SDLAT. In a multiple regression analysis, SDLAT, amplitude/peak eye-lid closing velocity and blink duration predicted subjective sleepiness bouts with a sensitivity and specificity of about 70%, but were mutually redundant. The prediction of LCs gave considerably weaker, but similar results. In summary, SDLAT and eye closure variables could be candidates for use in sleepiness-monitoring devices. However, individual differences are considerable and there is need for research on how to identify and predict individual differences in susceptibility to sleepiness.
10.
Åkerstedt, Torbjörn, et al.
(författare)
Subjective sleepiness is a sensitive indicator of insufficient sleep and impaired waking function
2014
Ingår i: Journal of Sleep Research. - : Wiley. - 0962-1105 .- 1365-2869. ; 23:3, s. 240-252
Tidskriftsartikel (refereegranskat) abstract
The main consequence of insufficient sleep is sleepiness. While measures of sleep latency, continuous encephalographical/electro-oculographical (EEG/EOG) recording and performance tests are useful indicators of sleepiness in the laboratory and clinic, they are not easily implemented in large, real-life field studies. Subjective ratings of sleepiness, which are easily applied and unobtrusive, are an alternative, but whether they measure sleepiness sensitively, reliably and validly remains uncertain. This review brings together research relevant to these issues. It is focused on the Karolinska Sleepiness Scale (KSS), which is a nine-point Likert-type scale. The diurnal pattern of sleepiness is U-shaped, with high KSS values in the morning and late evening, and with great stability across years. KSS values increase sensitively during acute total and repeated partial sleep deprivation and night work, including night driving. The effect sizes range between 1.5 and 3. The relation to driving performance or EEG/EOG indicators of sleepiness is highly significant, strongly curvilinear and consistent across individuals. High (>6) KSS values are associated particularly with impaired driving performance and sleep intrusions in the EEG. KSS values are also increased in many clinical conditions such as sleep apnea, depression and burnout. The context has a strong influence on KSS ratings. Thus, physical activity, social interaction and light exposure will reduce KSS values by 1-2 units. In contrast, time-on-task in a monotonous context will increase KSS values by 1-2 units. In summary, subjective ratings of sleepiness as described here is as sensitive and valid an indicator of sleepiness as objective measures, and particularly suitable for field studies.
