Key Facts:

  • Driving while fatigued or sleepy leads to impairment of driving performance by increasing reaction times, reducing attention and compromising the driver’s ability to control their vehicle (Bartlett, 1953; Friswell & Williamson, 2008).

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

  • Fatigued drivers are more likely to be involved in an accident resulting in the fatal injury of themselves or their vehicle’s occupants than non-fatigued drivers (HVCIS database – Parkes, Gillan & Cynk, 2009).

  • Research has found that a person who drives after being awake for 17 hours has impaired driving skills comparable to a driver with a 0.05 mg/ml blood alcohol level. 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 of 0.1 mg/ml (Dawson & Reid, 1997; Williamson & Feyer, 2000).

  • Research shows that there are two daily peaks when fatigue accidents are most prevalent due to a dip in cognitive and motor function performance. 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 & Reyner, 1995; Eskandarian et al., 2007).

  • The behavioural effects of caffeine that have been empirically demonstrated include increased alertness, faster reaction times, improved accuracy on choice reaction, improved vigilance and improved tracking accuracy (Brice & Smith, 2002).

  • Use of energy drinks have shown significant improvement in driving performance, demonstrated by less varied speed, better lane keeping, fewer critical incidents and faster reaction times when compared with a placebo (Horne & Reyner, 2001; Parkes et al. 2005).

  • It is worth noting however that these effects are quite small and the authors have concluded that functional energy drinks should not be used as a perceived cure for driver sleepiness.

  • A simulator study found that the alerting effects of a rumble strip only lasted for up to five minutes before sleepiness returned (Anund et al., 2008).

  • Drivers with sleep apnoea are at a statistically significant increased risk of involvement in motor vehicle accidents, potentially two to three times higher than other drivers (Ellen et al., 2006).

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

  • Prophylactic (preventative) naps, taken in the afternoon between 2pm and 5pm and before sleep loss is accrued, have been shown in a study by Macchia et al. (2002) to be particularly advantageous 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, naps were demonstrated to lead to 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: 26 Jan 2017, 04:14 PM