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Med Sci Law OnlineFirst, published on January 19, 2015 as doi:10.1177/0025802414556578
Keele Medico-Legal Seminar Feature Medicine, Science and the Law 0(0) 1–3 ! The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0025802414556578 msl.sagepub.com
Sleep-related road collisions Jim Horne and John Rumbold
Sleep-related collisions are a significant contributor to road traffic mortality, as they are common and more likely to be fatal. This article lists the factors that can identify these collisions, typified by micro-sleeps following periods of increasing sleepiness which are selfevident for the driver. The warning signs and effective countermeasures are highlighted. The law relating to drowsiness and driving is described. An important medical cause for these collisions is obstructive sleep apnoea (OSA), which is highly prevalent among heavy goods vehicle (HGV) drivers. The treatment for OSA and the need for screening of HGV drivers are discussed.
eliminated these, it is likely that the otherwise healthy driver had fallen asleep, having had a ‘micro-sleep’, following a period of increasing sleepiness of which he/she would have been aware.2 Evidence in support of this type of collision has to depend on objective information. In particular, an evidence-based timeline of the driver’s activities over at least the previous 48 hours needs to be compiled, in order to try and establish what their sleep pattern had been like, and the extent to which prior sleep may have been inadequate.3
Vulnerable groups Characteristics
SRCs account for at least 10% of all road accidents attended by the police, increasing to an overall 23% on motorways and other monotonous roads.1 In the early hours of the morning, when the body clock is in its daily trough, and coupled with both sleep loss and further monotony, this latter figure increases to 50%. SRCs probably cause more fatalities than alcohol, especially as SRCs are more likely to involve death and fatal injury because of the higher speed at impact without braking.2 There are three groups that are at greater risk for SRCs. The first group is younger drivers, as they are not only more vulnerable to sleepiness, but are overconfident and will deny the likelihood that they will fall asleep and continue driving.1 The second group is shift workers returning home at around 6–7 am after the first night of a 12hour night shift when it is likely that they have been awake for around 24 hours and are still within the ‘danger zone’ of their body clock.4,5 The third group comprises occupational drivers with obstructive sleep apnoea and hypopnoea syndrome (OSAHS) a condition of obstructed breathing during sleep which causes severe sleep disruption and thus excessive daytime sleepiness. Predisposing factors for OSAHS comprise: obesity, being a male aged over 50 years,
In sleep-related collisions (SRCs), the vehicle typically runs off the road and/or collides with another vehicle or object. This happens because of the cessation of the usual continuous corrective steering movements or braking required to keep the vehicle in a lane or at a safe distance from a vehicle in front, resulting in the vehicle ‘following its own path’, depending on the vehicle, road camber, wind and other factors. A vehicle being driven by a sleepy driver may or may not slow down, depending on the foot pressure required to depress the accelerator, and whether the return spring in the accelerator pedal is of sufficient strength to push the foot upwards when the leg and foot muscles relax, as happens when falling asleep at the wheel. A key sign of such a collision is the absence of any skid marks or other signs of hard braking or avoidance manoeuvres beforehand. It has to be established that immediately prior to the collision, the driver concerned could have seen clearly for at least 15 seconds before the point of run-off or the moment the object was hit, so that avoidance procedures could have easily been taken – that is, the collision was not the result of momentary distraction but relatively prolonged inattention, and thus the driver was probably not conscious. Other potential causes of the collision have to Sleep Research Centre, Loughborough University, Leicestershire, UK be eliminated, particularly a mechanical defect of the vehicle, bad weather, poor road conditions, driving too Corresponding author: fast or close to the vehicle in front, alcohol, non-preJim Horne, Sleep Research Centre, Loughborough University, scribed and prescribed drugs, and illness of the driver Leicestershire LE11 3TU, UK. (e.g. the driver had a fit, faint or funny turn).1 Having Email: [email protected] Downloaded from msl.sagepub.com at University of Otago Library on July 4, 2015
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especially if the neck is fat (collar size >17 inches/ 44 cm). HGV drivers are prone to obesity, largely because of their lifestyle. A recent study showed that 25% of truckers are obese (body mass index [BMI] >30 kg/m2), with 15% of them (4% of all truckers) probably having at least some (undiagnosed) OSA (heavy snoring and an Epworth Sleepiness Scale score >11). Around 20,000 out of 500,000 UK truck drivers could be affected.6 Other risk factors for truck drivers are a high exposure to driving (averaging 100,000 km/year), more likely to drive at night during the ‘trough’ and being permitted to drive for up to four hours at night without a break. SRCs caused by trucks are: 1. twice as likely (as car collision) to result in death; 2. the most common cause of truck collision and the most likely cause of the truck and its load being destroyed (E1.5 million); and 3. the largest single cause of death during any type of work (including building sites). Furthermore, the usual central crash barriers will not stop a 40 tonne truck travelling at 57 mph (on its speed limiter, without braking), and on entering the opposite carriageway, there is a high probability that it will collide with oncoming vehicles. It will crush at least the first car and its occupants if it hits a queue of stationary vehicles.
Driver responsibility Countermeasures to falling asleep at the wheel such as opening the window, blowing cold air on the face, or turning the radio up are only effective for a matter of minutes. Stop driving and ‘take a 30 minute break’ is wise advice. During this break, consume a caffeinated drink (of known caffeine content – at least 80 mg of caffeine) and immediately return to the safely parked vehicle and take a 15–20-minute nap before the caffeine kicks in (which takes around 20 minutes). The caffeine plus nap combined in this way can be very effective,7 with this method recommended in the UK Highway Code. As Kay v Butterworth demonstrates, the driver has a responsibility when feeling drowsy to stop driving: If a driver allows himself to drive while he is asleep, he is at least guilty of the offence of driving without due care and attention because it is his business to keep awake. If drowsiness overtakes a driver while he is at the wheel, he should stop and wait until he shakes it off and is wide awake again . . . In the present case the driver must have known that drowsiness was overtaking him. (Humphreys, J)8
to have been asleep for at least a minute or so.9 Waking someone up from an unscheduled sleep of less than this period of time usually results in the sleeper’s genuine disbelief of having been asleep. Given that most drivers who fall asleep at the wheel cannot drive for such a length of time without spontaneously awaking or having a collision, it is not surprising that they have poor or no recollection of having fallen asleep. Also, because they were falling asleep or actually were asleep at the time of the collision, they often have little recollection of the events immediately prior to it. Nevertheless, prior to falling asleep at the wheel, drivers are aware of being sleepy, especially if they are driving in the early morning when they would normally be asleep and have been awake continuously throughout the previous day and that night. With the possible exception of certain clinical conditions (e.g. narcolepsy), sleep does not occur spontaneously from an alert state. There is a feeling of (often profound) sleepiness beforehand. It is not possible to be alert one minute and asleep the next. Sleep is portended by a feeling of increasing sleepiness. However, despite being very sleepy, drivers often deny the likelihood of actually falling asleep and believe that they can successfully fight sleep. Drivers who fall asleep in the small hours of the morning know beforehand that they feel sleepy. They will reach a point of ‘fighting sleep’ by performing acts such as opening the window (for fresh air), turning up the radio, stretching and so on, which by the very nature of these acts must demonstrate to the driver that they are sleepy. Sleep is a dangerous state, and all living organisms are provided with behaviours necessary to ensure that they do not fall asleep spontaneously, and have forewarning to allow them to reach a place of relative safety. Sleepiness itself clouds one’s memory, and it is common for sleepy drivers to have little subsequent recollection of the events during the period of sleepiness. This phenomenon applies to everyone – few people can accurately remember how sleepy they were before bedtime last night and in particular when they became aware of this. The same applies to hunger and thirst – one can seldom remember either in any detail a few hours after a meal or drink, even though it was clear at the time that one was hungry/thirsty. The human brain does not have the capacity to remember such pointless information after the consummatory acts of sleeping, eating and drinking.
Micro-sleeps
Falling asleep at the wheel culminates in a series ‘micro-sleeps’, typified by slow closure of the eyelids followed by slow opening (also called ‘eye-rolling’), There are warning signs before someone falls usually lasting about five to seven seconds in total, asleep at the wheel prior to the micro-sleep which typbut this can be for much longer as micro-sleeps proically lasts around five to seven seconds. However, in gress (see below). Needless to say, the eyes order to be ‘aware’ that one has beenDownloaded asleep, one has from msl.sagepub.com at University of Otago Library on July 4, 2015
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Horne and Rumbold are unseeing, the brain is in light sleep and steering movements cease and the vehicle may drift. If the driver wakes up in time, there will be momentary confusion and sudden, violent braking and/or steering correction. The driver may become more alert for a while, often only for a minute or so, when another micro-sleep appears. The process repeats itself, with micro-sleeps becoming longer and, maybe, a collision. Sometimes, in sleepy drivers determined to stay awake, micro-sleeps appear (as before) without eye closure, but with a blank, trance-like staring through the windscreen. Again, the eyes are unseeing. ‘Head nodding’ does not always occur during micro-sleeps as the inclination of the driver’s seat and the driver’s posture may counteract this tendency.
‘Irrelevant states’ ‘Highway hypnosis’ as described in the AttorneyGeneral’s Reference (No 2 of 1992)10 does not exist. One cannot be hypnotised by the roadway – it is sleepiness because the driver is sleepy. An alert driver cannot be made sleepy (de novo) by the road conditions. Sleepiness has to exist in the driver to begin with. ‘Driving without awareness’ – that is, not being able to remember one’s driving for the last 10 minutes or so – is not necessarily a sign of falling asleep at the wheel, merely that the driver was probably on a familiar and unstimulating route and had his/her mind on other matters, but was still competent to drive. One can be watching a dull TV programme or reading a newspaper, but have one’s mind ‘elsewhere’, to the extent that nothing was being remembered. However, one still remains alert to any new stimulus.
OSAHS
3 programmes and divert drivers to non-driving work until they are fit to drive. Compliance with treatment is automatically monitored electronically by CPAP machines, and this compliance is mandatory for HGV drivers diagnosed with significant OSAHS. These screening programmes are cost-effective, costing the same as two or three truck tyres. Moreover, early diagnosis and treatment of OSAHS reduces the risk not only of road-traffic accidents, but also of cardiovascular disease, especially hypertension, myocardial infarction and stroke, all of which are more common in those with OSAHS. There have been European initiatives to promote awareness of driving and sleep such as the ‘Wake-Up Bus’ touring the European Union (http://www.esrs.eu/ committees-networks/eu-committee/esrs-wake-upbus.html), and presentations have been made on the issue of sleep and driving at the European Parliament. An EU-wide solution is important, given the numbers of truck drivers from the Continent on British roads.15 Greater education of truck drivers and employers could lead to a significant reduction in accidents. Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
References 1. Horne JA and Reyner LA. Sleep related vehicle accidents. BMJ 1995; 310: 565. 2. Horne J. Focus on sleep-related fatal vehicle crashes. J Homicide Major Incident Invest 2011; 7: 121. 3. Reyner LA and Horne JA. Early morning driver sleepiness: effectiveness of 200mg caffeine. Psychophys 2000; 37: 1–6. 4. NCSDR/NHTSA Expert Panel on Driver Fatigue and Sleepiness. Drowsy driving and automobile crashes, 1998; HS 808 707. 5. Gold DR, Rogacz S, Bock N, et al. Rotating shift work, sleep, and accidents related to sleepiness in hospital nurses. Am J Public Health 1992; 82: 1011–1014. 6. Filtness AJ. Obstructive sleep apnoea and daytime driver sleepiness. PhD Thesis: Loughborough University, UK, 2011. 7. Reyner LA and Horne J. Suppression of sleepiness in drivers: combination of caffeine with a short nap. Psychophysiology 1997; 34: 721. 8. Kay v Butterworth [1945] 61 TLR 452. 9. Horne JA and Reyner LA. Driver sleepiness. J Sleep Res 1995; 4: 23–29 . 10. Attorney-General’s Reference (No. 2 of 1992) [1994] QB 91. 11. R v Quick [1973] QB 910. 12. R v Sullivan [1983] 3 WLR 123. 13. R v Burgess [1991] 2 QB 92. 14. Filtness AJ, Reyner LA and Horne JA. Moderate sleep restriction in treated older male OSA participants: greater impairment during monotonous driving compared with controls. Sleep Med 2011; 12: 838 . 15. Alonderis A, Barbe´ F, Bonsignore M, et al. Medicolegal implications of sleep apnoea syndrome: driving license regulations in Europe. Sleep Med 2008; 9: 362 .
Where the person has OSAHS, they may well be less aware of sleepiness. They become accustomed to falling asleep frequently for whatever reason and are often unaware of the real cause. They only appreciate how sleepy they were after the commencement of effective treatment (most commonly from the provision of a machine to help breathing during sleep – a continuous positive airway pressure [CPAP] machine). OSAHS as an internal cause can result in an insane automatism (see Quick, Sullivan and Burgess).11–13 Treatment of OSAHS with CPAP is effective rapidly, although patients remain more vulnerable to sleep deprivation and even one night without effective treatment will result in recurrence of the symptoms.14 HGV drivers are aware that untreated OSAHS will mean they cannot drive, and thus they may conceal symptoms. Routine HGV medicals do not detect OSAHS. However, HGV drivers diagnosed with OSAHS are unlikely to lose their licences, and most can be back on the road within three to four weeks of treatment. Some companies have screening Downloaded from msl.sagepub.com at University of Otago Library on July 4, 2015
(MSL)
[1–3] [PREPRINTER stage]
Med Sci Law OnlineFirst, published on January 19, 2015 as doi:10.1177/0025802414556578
Keele Medico-Legal Seminar Feature Medicine, Science and the Law 0(0) 1–3 ! The Author(s) 2015 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0025802414556578 msl.sagepub.com
Sleep-related road collisions Jim Horne and John Rumbold
Sleep-related collisions are a significant contributor to road traffic mortality, as they are common and more likely to be fatal. This article lists the factors that can identify these collisions, typified by micro-sleeps following periods of increasing sleepiness which are selfevident for the driver. The warning signs and effective countermeasures are highlighted. The law relating to drowsiness and driving is described. An important medical cause for these collisions is obstructive sleep apnoea (OSA), which is highly prevalent among heavy goods vehicle (HGV) drivers. The treatment for OSA and the need for screening of HGV drivers are discussed.
eliminated these, it is likely that the otherwise healthy driver had fallen asleep, having had a ‘micro-sleep’, following a period of increasing sleepiness of which he/she would have been aware.2 Evidence in support of this type of collision has to depend on objective information. In particular, an evidence-based timeline of the driver’s activities over at least the previous 48 hours needs to be compiled, in order to try and establish what their sleep pattern had been like, and the extent to which prior sleep may have been inadequate.3
Vulnerable groups Characteristics
SRCs account for at least 10% of all road accidents attended by the police, increasing to an overall 23% on motorways and other monotonous roads.1 In the early hours of the morning, when the body clock is in its daily trough, and coupled with both sleep loss and further monotony, this latter figure increases to 50%. SRCs probably cause more fatalities than alcohol, especially as SRCs are more likely to involve death and fatal injury because of the higher speed at impact without braking.2 There are three groups that are at greater risk for SRCs. The first group is younger drivers, as they are not only more vulnerable to sleepiness, but are overconfident and will deny the likelihood that they will fall asleep and continue driving.1 The second group is shift workers returning home at around 6–7 am after the first night of a 12hour night shift when it is likely that they have been awake for around 24 hours and are still within the ‘danger zone’ of their body clock.4,5 The third group comprises occupational drivers with obstructive sleep apnoea and hypopnoea syndrome (OSAHS) a condition of obstructed breathing during sleep which causes severe sleep disruption and thus excessive daytime sleepiness. Predisposing factors for OSAHS comprise: obesity, being a male aged over 50 years,
In sleep-related collisions (SRCs), the vehicle typically runs off the road and/or collides with another vehicle or object. This happens because of the cessation of the usual continuous corrective steering movements or braking required to keep the vehicle in a lane or at a safe distance from a vehicle in front, resulting in the vehicle ‘following its own path’, depending on the vehicle, road camber, wind and other factors. A vehicle being driven by a sleepy driver may or may not slow down, depending on the foot pressure required to depress the accelerator, and whether the return spring in the accelerator pedal is of sufficient strength to push the foot upwards when the leg and foot muscles relax, as happens when falling asleep at the wheel. A key sign of such a collision is the absence of any skid marks or other signs of hard braking or avoidance manoeuvres beforehand. It has to be established that immediately prior to the collision, the driver concerned could have seen clearly for at least 15 seconds before the point of run-off or the moment the object was hit, so that avoidance procedures could have easily been taken – that is, the collision was not the result of momentary distraction but relatively prolonged inattention, and thus the driver was probably not conscious. Other potential causes of the collision have to Sleep Research Centre, Loughborough University, Leicestershire, UK be eliminated, particularly a mechanical defect of the vehicle, bad weather, poor road conditions, driving too Corresponding author: fast or close to the vehicle in front, alcohol, non-preJim Horne, Sleep Research Centre, Loughborough University, scribed and prescribed drugs, and illness of the driver Leicestershire LE11 3TU, UK. (e.g. the driver had a fit, faint or funny turn).1 Having Email: [email protected] Downloaded from msl.sagepub.com at University of Otago Library on July 4, 2015
XML Template (2015) [12.1.2015–3:02pm] //blrnas3.glyph.com/cenpro/ApplicationFiles/Journals/SAGE/3B2/MSLJ/Vol00000/140047/APPFile/SG-MSLJ140047.3d
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Medicine, Science and the Law 0(0)
especially if the neck is fat (collar size >17 inches/ 44 cm). HGV drivers are prone to obesity, largely because of their lifestyle. A recent study showed that 25% of truckers are obese (body mass index [BMI] >30 kg/m2), with 15% of them (4% of all truckers) probably having at least some (undiagnosed) OSA (heavy snoring and an Epworth Sleepiness Scale score >11). Around 20,000 out of 500,000 UK truck drivers could be affected.6 Other risk factors for truck drivers are a high exposure to driving (averaging 100,000 km/year), more likely to drive at night during the ‘trough’ and being permitted to drive for up to four hours at night without a break. SRCs caused by trucks are: 1. twice as likely (as car collision) to result in death; 2. the most common cause of truck collision and the most likely cause of the truck and its load being destroyed (E1.5 million); and 3. the largest single cause of death during any type of work (including building sites). Furthermore, the usual central crash barriers will not stop a 40 tonne truck travelling at 57 mph (on its speed limiter, without braking), and on entering the opposite carriageway, there is a high probability that it will collide with oncoming vehicles. It will crush at least the first car and its occupants if it hits a queue of stationary vehicles.
Driver responsibility Countermeasures to falling asleep at the wheel such as opening the window, blowing cold air on the face, or turning the radio up are only effective for a matter of minutes. Stop driving and ‘take a 30 minute break’ is wise advice. During this break, consume a caffeinated drink (of known caffeine content – at least 80 mg of caffeine) and immediately return to the safely parked vehicle and take a 15–20-minute nap before the caffeine kicks in (which takes around 20 minutes). The caffeine plus nap combined in this way can be very effective,7 with this method recommended in the UK Highway Code. As Kay v Butterworth demonstrates, the driver has a responsibility when feeling drowsy to stop driving: If a driver allows himself to drive while he is asleep, he is at least guilty of the offence of driving without due care and attention because it is his business to keep awake. If drowsiness overtakes a driver while he is at the wheel, he should stop and wait until he shakes it off and is wide awake again . . . In the present case the driver must have known that drowsiness was overtaking him. (Humphreys, J)8
to have been asleep for at least a minute or so.9 Waking someone up from an unscheduled sleep of less than this period of time usually results in the sleeper’s genuine disbelief of having been asleep. Given that most drivers who fall asleep at the wheel cannot drive for such a length of time without spontaneously awaking or having a collision, it is not surprising that they have poor or no recollection of having fallen asleep. Also, because they were falling asleep or actually were asleep at the time of the collision, they often have little recollection of the events immediately prior to it. Nevertheless, prior to falling asleep at the wheel, drivers are aware of being sleepy, especially if they are driving in the early morning when they would normally be asleep and have been awake continuously throughout the previous day and that night. With the possible exception of certain clinical conditions (e.g. narcolepsy), sleep does not occur spontaneously from an alert state. There is a feeling of (often profound) sleepiness beforehand. It is not possible to be alert one minute and asleep the next. Sleep is portended by a feeling of increasing sleepiness. However, despite being very sleepy, drivers often deny the likelihood of actually falling asleep and believe that they can successfully fight sleep. Drivers who fall asleep in the small hours of the morning know beforehand that they feel sleepy. They will reach a point of ‘fighting sleep’ by performing acts such as opening the window (for fresh air), turning up the radio, stretching and so on, which by the very nature of these acts must demonstrate to the driver that they are sleepy. Sleep is a dangerous state, and all living organisms are provided with behaviours necessary to ensure that they do not fall asleep spontaneously, and have forewarning to allow them to reach a place of relative safety. Sleepiness itself clouds one’s memory, and it is common for sleepy drivers to have little subsequent recollection of the events during the period of sleepiness. This phenomenon applies to everyone – few people can accurately remember how sleepy they were before bedtime last night and in particular when they became aware of this. The same applies to hunger and thirst – one can seldom remember either in any detail a few hours after a meal or drink, even though it was clear at the time that one was hungry/thirsty. The human brain does not have the capacity to remember such pointless information after the consummatory acts of sleeping, eating and drinking.
Micro-sleeps
Falling asleep at the wheel culminates in a series ‘micro-sleeps’, typified by slow closure of the eyelids followed by slow opening (also called ‘eye-rolling’), There are warning signs before someone falls usually lasting about five to seven seconds in total, asleep at the wheel prior to the micro-sleep which typbut this can be for much longer as micro-sleeps proically lasts around five to seven seconds. However, in gress (see below). Needless to say, the eyes order to be ‘aware’ that one has beenDownloaded asleep, one has from msl.sagepub.com at University of Otago Library on July 4, 2015
XML Template (2015) [12.1.2015–3:02pm] //blrnas3.glyph.com/cenpro/ApplicationFiles/Journals/SAGE/3B2/MSLJ/Vol00000/140047/APPFile/SG-MSLJ140047.3d
(MSL)
[1–3] [PREPRINTER stage]
Horne and Rumbold are unseeing, the brain is in light sleep and steering movements cease and the vehicle may drift. If the driver wakes up in time, there will be momentary confusion and sudden, violent braking and/or steering correction. The driver may become more alert for a while, often only for a minute or so, when another micro-sleep appears. The process repeats itself, with micro-sleeps becoming longer and, maybe, a collision. Sometimes, in sleepy drivers determined to stay awake, micro-sleeps appear (as before) without eye closure, but with a blank, trance-like staring through the windscreen. Again, the eyes are unseeing. ‘Head nodding’ does not always occur during micro-sleeps as the inclination of the driver’s seat and the driver’s posture may counteract this tendency.
‘Irrelevant states’ ‘Highway hypnosis’ as described in the AttorneyGeneral’s Reference (No 2 of 1992)10 does not exist. One cannot be hypnotised by the roadway – it is sleepiness because the driver is sleepy. An alert driver cannot be made sleepy (de novo) by the road conditions. Sleepiness has to exist in the driver to begin with. ‘Driving without awareness’ – that is, not being able to remember one’s driving for the last 10 minutes or so – is not necessarily a sign of falling asleep at the wheel, merely that the driver was probably on a familiar and unstimulating route and had his/her mind on other matters, but was still competent to drive. One can be watching a dull TV programme or reading a newspaper, but have one’s mind ‘elsewhere’, to the extent that nothing was being remembered. However, one still remains alert to any new stimulus.
OSAHS
3 programmes and divert drivers to non-driving work until they are fit to drive. Compliance with treatment is automatically monitored electronically by CPAP machines, and this compliance is mandatory for HGV drivers diagnosed with significant OSAHS. These screening programmes are cost-effective, costing the same as two or three truck tyres. Moreover, early diagnosis and treatment of OSAHS reduces the risk not only of road-traffic accidents, but also of cardiovascular disease, especially hypertension, myocardial infarction and stroke, all of which are more common in those with OSAHS. There have been European initiatives to promote awareness of driving and sleep such as the ‘Wake-Up Bus’ touring the European Union (http://www.esrs.eu/ committees-networks/eu-committee/esrs-wake-upbus.html), and presentations have been made on the issue of sleep and driving at the European Parliament. An EU-wide solution is important, given the numbers of truck drivers from the Continent on British roads.15 Greater education of truck drivers and employers could lead to a significant reduction in accidents. Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.
References 1. Horne JA and Reyner LA. Sleep related vehicle accidents. BMJ 1995; 310: 565. 2. Horne J. Focus on sleep-related fatal vehicle crashes. J Homicide Major Incident Invest 2011; 7: 121. 3. Reyner LA and Horne JA. Early morning driver sleepiness: effectiveness of 200mg caffeine. Psychophys 2000; 37: 1–6. 4. NCSDR/NHTSA Expert Panel on Driver Fatigue and Sleepiness. Drowsy driving and automobile crashes, 1998; HS 808 707. 5. Gold DR, Rogacz S, Bock N, et al. Rotating shift work, sleep, and accidents related to sleepiness in hospital nurses. Am J Public Health 1992; 82: 1011–1014. 6. Filtness AJ. Obstructive sleep apnoea and daytime driver sleepiness. PhD Thesis: Loughborough University, UK, 2011. 7. Reyner LA and Horne J. Suppression of sleepiness in drivers: combination of caffeine with a short nap. Psychophysiology 1997; 34: 721. 8. Kay v Butterworth [1945] 61 TLR 452. 9. Horne JA and Reyner LA. Driver sleepiness. J Sleep Res 1995; 4: 23–29 . 10. Attorney-General’s Reference (No. 2 of 1992) [1994] QB 91. 11. R v Quick [1973] QB 910. 12. R v Sullivan [1983] 3 WLR 123. 13. R v Burgess [1991] 2 QB 92. 14. Filtness AJ, Reyner LA and Horne JA. Moderate sleep restriction in treated older male OSA participants: greater impairment during monotonous driving compared with controls. Sleep Med 2011; 12: 838 . 15. Alonderis A, Barbe´ F, Bonsignore M, et al. Medicolegal implications of sleep apnoea syndrome: driving license regulations in Europe. Sleep Med 2008; 9: 362 .
Where the person has OSAHS, they may well be less aware of sleepiness. They become accustomed to falling asleep frequently for whatever reason and are often unaware of the real cause. They only appreciate how sleepy they were after the commencement of effective treatment (most commonly from the provision of a machine to help breathing during sleep – a continuous positive airway pressure [CPAP] machine). OSAHS as an internal cause can result in an insane automatism (see Quick, Sullivan and Burgess).11–13 Treatment of OSAHS with CPAP is effective rapidly, although patients remain more vulnerable to sleep deprivation and even one night without effective treatment will result in recurrence of the symptoms.14 HGV drivers are aware that untreated OSAHS will mean they cannot drive, and thus they may conceal symptoms. Routine HGV medicals do not detect OSAHS. However, HGV drivers diagnosed with OSAHS are unlikely to lose their licences, and most can be back on the road within three to four weeks of treatment. Some companies have screening Downloaded from msl.sagepub.com at University of Otago Library on July 4, 2015
