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Sleep related vehicle accidents

BMJ 1995; 310 doi: (Published 04 March 1995) Cite this as: BMJ 1995;310:565
  1. J A Horne, professora,
  2. L A Reyner, research associatea
  1. a Sleep Research Laboratory, Department of Human Sciences, Loughborough University, Leicestershire LE11 3TU
  1. Correspondence to: Professor Horne.
  • Accepted 30 December 1994


Objectives: To assess the incidence, time of day, and driver morbidity associated with vehicle accidents where the most likely cause was the driver falling asleep at the wheel.

Design: Two surveys were undertaken, in southwest England and the midlands, by using police databases or on the spot interviews.

Subjects: Drivers involved in 679 sleep related vehicle accidents.

Results: Of all vehicle accidents to which the police were summoned, sleep related vehicle accidents comprised 16% on major roads in southwest England, and over 20% on midland motorways. During the 24 hour period there were three major peaks: at around 0200, 0600, and 1600. About half these drivers were men under 30 years; few such accidents involved women.

Conclusions: Sleep related vehicle accidents are largely dependent on the time of day and account for a considerable proportion of vehicle accidents, especially those on motorways and other monotonous roads. As there are no norms for the United Kingdom on road use by age and sex for time of day with which to compare these data, we cannot determine what the hourly exposure v risk factors are for these subgroups. The findings are in close agreement with those from other countries.

Key messages

  • Key messages

  • Such accidents accounted for about 16% of road accidents in general and over 20% for motorways

  • There were clear time of day (circadian) effects with the most vulnerable times being around 2-7 am and in the mid-afternoon

  • Young male drivers accounted for half these accidents, but it is unknown whether these men are more exposed or are particularly at risk

  • The morbidity and mortality associated with sleep related accidents is higher, probably because of the greater speed on impact


    • Accepted 30 December 1994
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