In the next two posts, I will take a look at a couple of studies focusing on the effect of pharmacological and training interventions on driving performance. Driving simulators are very useful in examining the response to specific interventions on driving performance.
Mets and her Dutch colleagues designed a study to examine whether an over-the-counter stimulant drink could counteract the effect of sleepiness during prolonged driving. They split healthy controls subjects into three groups and studied their driving performance in a four hour driving simulation. The three groups were:
- Group 1: Two hours of driving followed by a 15 minute break with consumption of a 250-ml Red Bull Energy Drink followed by two additional hours driving
- Group 2: Two hours of driving followed by a 15 minute break with consumption of a placebo Red Bull drink (a Red Bull Energy drink without caffeine, taurine, glucuronolactone, inosotil and vitamin B complex)
- Group 3: Four hours of driving without a break, Red Bull or Red Bull placebo
Subjects were instructed to drive their simulated car in a steady manner while maintaining a steady speed of 95 km/hour (59.3 mph). The primary driving performance outcome measure was a variable standard deviation of lateral position (SDLP) an estimate of amount of weaving while driving. This variable has been shown to be a valid measure of attention and psychomotor driving performance sensitive to the effects of sleepiness, alcohol and other sedative drug use.
The key findings from the studied included:
- All groups showed more higher SDLP scores in driving hour two compared to driving hour one
- The Red Bull group showed a decrease in SDLP scores in driving hours three and four compared to placebo and group 3 performance
- The Red Bull group also showed reduction in the variability of speed
- The Red Bull group had lower levels of subjective sleepiness during driving hours three and four
The results are really not surprising and are in the direction of prediction. However, the study does provide for laboratory confirmation of what many have suspected. Over-the-counter stimulant drinks do provide an increase in alertness and this translates into better driving performance.
The study I would like to see is a comparison of driving performance of Red Bull energy drink compared to caffeine alone. Red Bull energy drink contains 80 mg of caffeine, approximately the equivalent of one strong cup of coffee. Whether the other non-caffeine components of Red Bull contribute to improved driving performance is not addressed in the current study.
One should not take from this study it all right to drive long distances as long as you take along plenty Red Bull or other stimulant drinks. Driving is best limited to short distances, changing of drivers if possible on long distance drives and never driving when sleep deprived or being drowsy from any cause.
This study does not provide information about driving for more than four hours or consumption of multiple doses of Red Bull or other stimulant containing substances over longer periods. It was done in a sample of healthy adult volunteers between the ages of 21 and 35 years. You cannot generalize the results of this study to older individuals, individuals drinking alcohol, individuals taking medications or individuals with any chronic medical illness.
Nevertheless, the study confirms by laboratory driving simulation the effect many have known. A driving break along with consumption of a caffeine-containing substance seems to make longer drives more tolerable and may improve driving performance.
Disclosure: This study was funded by the maker of Red Bull Gmbh. The received no compensation from Red Bull for selecting or posting commentary on this study.
Photo of a Mandarin duck from Busch Gardens in Tampa, Florida is from the author's files.
Howland J, Rohsenow DJ, Arnedt JT, Bliss CA, Hunt SK, Calise TV, Heeren T, Winter M, Littlefield C, & Gottlieb DJ (2011). The acute effects of caffeinated versus non-caffeinated alcoholic beverage on driving performance and attention/reaction time. Addiction (Abingdon, England), 106 (2), 335-41 PMID: 21134017