The impact of having a 15-min break with and without consuming an energy drink on prolonged simulated highway driving

Purpose: To examine whether consuming an energy drink while having a break is effective in reducing the number of lapses of attention during prolonged highway driving. Methods: In a double-blind crossover study, N = 21 healthy volunteers performed a 4-h driving test in the STISIM driving simulator. After 2h, a 15-min break was scheduled. During the break, participants consumed either 250 ml of energy drink (ED) (Red Bull) or a placebo drink (Red Bull without caffeine (80 mg), glucuronolactone, taurine and B-vitamins). Participants were instructed to drive 95 km/h with a steady lateral position. Primary outcome was the number (#) of lapses; i.e., short periods of inattention defined by a deviation from the chosen lateral position for > 100 cm for 8 s or more. Results: Having a break, without consuming energy drink, significantly reduced the number of lapses in the 3rd hour of driving (9.9 versus 7.4 lapses, p = 0.006). After placebo, the number of lapses in the 4th and 2nd hour were identical (9.9 and 9.9 lapses, p = 1.000). Consuming and energy drink during the break resulted in a significant reduction in lapses in the 3rd hour (4.3 versus 9.2, p = 0.012) and 4th hour of driving (6.2 versus 9.2 lapses, p = 0.041), when compared with the 2nd hour of driving. Conclusion: Consuming an energy drink while having a 15-min break significantly reduces the number of lapses during prolonged highway driving, and to a greater extent than having a break only.