Dr. Tony Wright
To ask the Secretary of State for the Environment, Transport and the Regions what estimate he has made of the number of road accidents caused by drivers falling asleep. 
§ Ms Glenda Jackson
There is no national estimate of the number of accidents caused by drivers falling asleep. However, research has shown that tiredness is a principal factor in around 10 per cent. of all accidents. Accordingly, it is estimated that around 23,000–24,000 injury accidents a year result from driver fatigue.