Prevalence of driver sleepiness in a random population-based sample of car driving

Abstract

Study objectives: To obtain reliable estimates of the prevalence of driver sleepiness.

Design: A two-stage cluster sampling technique was employed to obtain a sample of car drivers representative of time spent driving on public roads in a geographically defined region. Data were collected by interviewer-administered questionnaire, and analysed in accordance with the sampling design.

Setting: The Auckland region of New Zealand, between April 1998 and July 1999.

Participants: 588 drivers of cars and other light vehicles recruited at 69 roadside survey sites.

Measurements and results: Of 746 eligible participants, 79% were interviewed, 12% refused, 8% were untraceable, and 1% were unable to give informed consent. From this sample we estimated that 58.7% of driving was undertaken by men. The vast majority of driving (90.8%) was undertaken by drivers with Epworth Sleepiness scores in the normal range (<10), but a significant minority was undertaken by drivers with one or more characteristics likely to impair alertness. 3.1% had < or = 5 hours sleep in the previous 24 hours, and 21.9% had < or = 4 full nights sleep in the previous week. The triad of symptoms associated with sleep apnea (snoring, choking, and breathing pauses while sleeping) was present in 1.6%; and 8.1% worked a pattern of shifts likely to interfere with normal sleep.

Conclusion: The prevalence of sleepiness amongst a random sample of New Zealand car driving was low, and less than suggested by previous studies.