Effects of coffee on driving performance during prolonged simulated highway driving.
BACKGROUND
Coffee is often consumed to counteract driver sleepiness. There is limited information on the effects of a single low dose of coffee on prolonged highway driving in non-sleep deprived individuals.


OBJECTIVE
The aim of this study was to examine the effects of a single cup of coffee (80 mg caffeine) on simulated highway driving performance.


METHODS
Non-sleep deprived healthy volunteers (n024) participated in a double-blind, placebo-controlled, crossover study. After 2 h of monotonous highway driving, subjects received caffeinated or decaffeinated coffee during a 15-min break before continuing driving for another 2 h. The primary outcome measure was the standard deviation of lateral position (SDLP), reflecting the weaving of the car. Secondary outcome measures were speed variability, subjective sleepiness, and subjective driving performance.


RESULTS
The results showed that caffeinated coffee significantly reduced SDLP as compared to decaffeinated coffee, both in the first (p00.024) and second hour (p00.019) after the break. Similarly, the standard deviation of speed (p0 0.024; p00.001), mental effort (p00.003; p00.023), and subjective sleepiness (p00.001; p00.002) were reduced in both the first and second hour after consuming caffeinated coffee. Subjective driving quality was significantly improved in the first hour after consuming caffeinated coffee (p00.004).


CONCLUSIONS
These findings demonstrate a positive effect of one cup of caffeinated coffee on driving performance and subjective sleepiness during monotonous simulated highway driving.
Division of Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Universiteitsweg 99, 3584 CG Utrecht, The Netherlands. M.A.J.Mets@uu.nl
M  A  J
M
Mets
D
D
Baas
I
I
van Boven
B
B
Olivier
J  C
J
Verster
D001334:Automobile Driving; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D000697:Central Nervous System Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D003069:Coffee; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D013997:Time Factors; D014851:Wakefulness / Q000187:drug effects; D055815:Young Adult
D000697:Central Nervous System Stimulants; D003069:Coffee; D002110:Caffeine