Drowsiness, counter-measures to drowsiness, and the risk of a motor vehicle crash.
OBJECTIVE
Knowledge of how different indicators of drowsiness affect crash risk might be useful to drivers. This study sought to estimate how drowsiness related factors, and factors that might counteract drowsiness, are related to the risk of a crash.


METHODS
Drivers on major highways in a rural Washington county were studied using a matched case-control design. Control (n=199) drivers were matched to drivers in crashes (n=200) on driving location, travel direction, hour, and day of the week.


RESULTS
Crash risk was greater among drivers who felt they were falling asleep (adjusted relative risk (aRR) 14.2, 95% confidence interval (CI) 1.4 to 147) and those who drove longer distances (aRR 2.2 for each additional 100 miles, 95% CI 1.4 to 3.3). Risk was also greater among drivers who had slept nine or fewer hours in the previous 48 hours, compared with those who had slept 12 hours. Crash risk was less for drivers who used a highway rest stop (aRR 0.5, 95% CI 0.3 to 1.0), drank coffee within the last two hours (aRR 0.5, 95% CI 0.3 to 0.9), or played a radio while driving (aRR 0.6, 95% CI .4 to 1.0).


CONCLUSIONS
Drivers may be able to decrease their risk of crashing if they: (1) stop driving if they feel they are falling asleep; (2) use highway rest stops; (3) drink coffee; (4) turn on a radio; (5) get at least nine hours sleep in the 48 hours before a trip; and (6) avoid driving long distances by sharing the driving or interrupting the trip.
Cummings
P
P
Harborview Injury Prevention and Research Center and the Department of Epidemiology, University of Washington, Seattle 98104-2499, USA. peterc@u.washington.edu
Koepsell
T D
TD
Moffat
J M
JM
Rivara
F P
FP
D000063:Accidents, Traffic / Q000517:prevention & control* / Q000706:statistics & numerical data; D000293:Adolescent; D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012306:Risk; D012894:Sleep Stages; D014861:Washington / Q000453:epidemiology