Discussion and Findings

  • Fatigue can result in both cognitive and motor function impairment caused through a reduction in physiological and psychological reductions in performance. Driving while fatigued or sleepy can lead to increased reaction times, reduce attention and compromise a drivers’ ability to control their vehicle (Bartlett, 1953; Friswell & Williamson, 2008).

  • After 17 hours of sustained wakefulness, a driver’s psychomotor performance decreases to a level equivalent to that of a driver with a blood alcohol concentration of 0.05mg/ml (Dawson & Reid, 1997). A driver who has gone without sleep for 24 hours has impaired driving skills comparable to a driver with an illegally high blood alcohol concentration (0.1 mg/ml) (Dawson & Reid, 1997; Williamson and Feyer, 2000). Fatigued drivers are more likely to be involved in an accident resulting in the fatal injury of themselves or their vehicle’s occupants than drivers involved in non-fatigue related accidents (HVCIS database – Parkes, Gillan, Cynk, 2009).

  • In the UK during 2016, fatigue was recorded by police as a contributory factor in 4% of fatal accidents and 2% of serious injury accidents (RRCGB, DfT, 2017). However, research suggests that sleep-related vehicle accidents are under-reported and in fact are more likely to account for 16% to 20% of all vehicle accidents in the UK (Horne & Reyner, 1995).

  • Sleep-related vehicle accidents are more common on long monotonous roads due to the lack of stimulating scenarios that are experienced in urban driving environments (Horne & Reyner, 2001).

  • Research shows that there are two daily peaks when fatigue accidents are most prevalent. The first is in the early hours of the morning; commonly accepted as 2.00am to 6.00am. The second peak occurs between 2.00pm and 4.00pm (Brown, 1994; Pack et al., 1995; Horne and Reyner, 1995; Eskandarian et al., 2007). A dip in cognitive and motor function performance at these times contributes to driver fatigue accident risk.

  • 85% of sleep-related vehicle accidents involve male drivers (Flatley, Reyner & Horne, 2004). Drivers under the age of 30 are most at-risk of being involved in a sleep-related vehicle accident (Horne & Reyner, 1995; Flatley, Reyner & Horne, 2004). A more recent study, undertaken by Filtness, Reyner & Horne (2011) reinforces the risk associated with fatigue and young drivers. This study also concludes that effects of sleepiness take longer to develop in older drivers, indicating that older drivers are less vulnerable to sleep-related driving impairment.

  • An analysis of over 600 truck accidents in Europe identified fatigue as the main cause in 6% of the accidents investigated, with 37% of these resulting in a fatality (International Road Transport Union, 2007). Accidents involving HGVs show an increased level of severity when the driver is fatigued (1.26 fatalities per accident involving a fatigued driver) in comparison with all HGV accidents (1.11 fatalities per accident involving a fatigued driver). PSV accidents involving a fatigued driver also show a high level of severity (2.00 fatalities per accident involving a fatigued driver) than for all PSV accidents (1.11 fatalities per accident involving a fatigued driver) (Parkes et al., 2009).


  • Despite evidence that they are ineffective, many drivers persist in using use a number of ad-hoc measures that they believe (erroneously) will combat fatigue, including opening the window, turning on the radio and talking to a passenger (Nordbakke & Sagberg, 2007; Oran-Gilad & Shinar, 2000). None of these measures have been shown to have a restorative effect on fatigued driving, and their continued use means that drivers tend to avoid measures that are effective (e.g. stopping and taking a nap).

  • Many vehicle manufacturers have implemented accident avoidance features in some of their vehicles. These systems provide opportunities to minimise the impact of an accident, which may result from severe fatigue or distraction. Although a review of technologies has already been made, an independent evaluation of their effectiveness has not been completed.

  • Cotter, Reed & Wright (2006, cited in Charman, 2009) conducted a review of eleven sleepiness detection devices. These included devices based on measurements of eye movements, driver behaviour (including steering and lane deviations), fatigue models, and on a combination of these approaches. The review showed that detection technologies available at the time of the review were being used to warn drivers of unexpected sleepiness rather than keep the driver awake. Jackson et al. (2011) further discuss this issue, suggesting that these types of devices only respond once a driver’s performance is already significantly impaired and that drivers may continue to drive until devices are activated, rather than acting responsibly when recognising that they are fatigued. Therefore, use of such devices should be treated with caution.

  • A study into the use of a lane monitoring system in Germany concluded that implementation would lead to a 35% reduction in lane changing related accidents (a significant proportion of which were a result of fatigue). This would equate to a 2.9% reduction in all vehicle accidents in Germany. These types of systems may also provide safety benefits within the UK.

  • The consumption of caffeine, through tea, coffee, cola or an energy drink, helps to increase alertness, produce faster reaction times, improve accuracy of decision making, improve vigilance and improve tracking accuracy (Brice & Smith, 2002). In addition, the use of an energy drink also results in significant improvement in driving performance, demonstrated by less varied speed and fewer critical incidents (Parkes et al., 2000).

  • Research in the USA showed that continuous hard shoulder rumble strips, also used along motorways in the UK, can reduce single-vehicle run-off road accidents by approximately 20% (Griffith, 1999; Hanley et al., 2000). However, the effect of rumble strips on approach to a change in speed limit, a roundabout, or road toll has only proven to be effective for up to five minutes (Anund et al., 2008). Research also suggests that drivers proactively rely on these features with 63% of surveyed drivers believing that rumble strips would wake them if they fall asleep Nordbakke & Sagberg (2007).

  • Studies in the USA, Australia and Sweden have indicated that Obstructive Sleep Apnoea is prevalent in 12% to 17% of professional drivers (Talmage et al., 2008; Parks et al., 2009; Howard et al., 2004; Carter et al., 2003). Estimates suggest that, in the UK, approximately 80% of people with sleep apnoea are either unaware or do not seek diagnosis (Gibson, 2005).

  • Continuous positive airway pressure (CPAP) is a treatment that uses mild air pressure, via a ventilator, to treat Obstructive Sleep Apnoea by keeping the airways open. This has consistently been shown to improve the driving performance and reduce the accident risk of sufferers of OSA by helping to reduce daytime sleepiness within two to seven days of treatment (Ellen et al., 2006; Tregear, Reston, Schoelles & Phillips B., 2010).

  • Work-related driving poses a considerable risk on UK roads and fatigue is a primary contributory factor. To combat driver fatigue the European Union has implemented a number of regulations and directives (Regulation EC 561/2006, Directive 2002/15/EC and Directive 2003/88/EC). Regulations and directives attempt to provide a standardised approach to limits on driving time and requirements on drivers to take minimum breaks and rest periods. An assessment of the effectiveness of these regulations and directives shows that some Member States suspect that certain employers maintain a system of double recording, falsifying records to allow drivers to work longer hours (European Union, 2012).

  • However, when identified, serious offences are reported immediately, which lead to a penal order or notification to the occupational safety and health authorities, who then determine whether more stringent monitoring of the company is required (European Union, 2010).

  • The most effective and efficient solution to fatigue is restorative rest, which must include sleep (BMA, 2004). Whilst short breaks have shown to improve performance and reduce subjective fatigue (Rosekind, Co & Gregory, 2000; Neri, Oyung % Colletti, 2002), other studies have shown that rest breaks for people suffering from fatigue ‘can decrease fatigue but not necessarily accident risk or errors’ (Rogers, Hwang & Scott, 2004).

  • Prophylactic (preventative) naps taken before sleep loss is accrued have been shown to be particularly advantageous in one study (Macchia et al., 2002), especially for night time truck drivers. There were limitations to the study; only eight drivers were used in a lab-based simulator, and data from three of these had to be discounted). Nonetheless, a three hour nap in the afternoon, between 2pm and 5pm, was shown to reduce the effects of fatigue during the following night’s shift resulting in faster and more consistent reaction times, reduced accident risk, and higher night time alertness up to 14 hours later Macchia et al. (2002).


  • Date Added: 03 Apr 2012, 08:13 AM
  • Last Update: 11 Dec 2017, 04:56 PM