An evaluation of energy drinks containing glucose and caffeine using the TRL driving simulator

  • Published: PPR059. Transport Research Laboratory (2005)
  • Authors: Parkes, A.M., York, I., Burton, S., Luke, T.
  • Date Added: 29 Dec 2013
  • Last Update: 25 Oct 2016
  • Format: html


Examine the effect of different levels of caffeine and glucose on driver fatigue.


The experiment was conducted using the TRL advanced full-mission driving simulator and provided a range of realistic traffic scenarios. 48 experienced drivers aged between 25 and 50 participated in this study. The sample was split evenly by gender. The study employed a double-blind, placebo controlled, repeated measures design. The three experimental conditions were: (1) Control drink (330ml, taste matched to energy drinks), (2) Level 1 energy drink (330ml, 60g glucose and 25mg caffeine), (3) Level 2 energy drink (330ml, 60g glucose and 40mg caffeine). These drinks were formulated in order to taste and appear the same in all conditions, the only difference being the caffeine and glucose dose. All participants were tested during the post lunch dip where natural alertness is at a low.

Key Findings:

  • Overall the results indicate an improvement in driving performance (lane keeping, reaction time and following performance) after drinking the level 2 drink (containing 40 mg caffeine and 60g glucose) compared to the control drink.

  • Some measures also showed a slight improvement with the level 1 drink (containing 25 mg caffeine and 60g glucose).


Driving simulator, glucose, caffeine, lane keeping, reaction time, following performance, alertness


It is clear from this research that there is a benefit in stopping the vehicle, consuming an energy drink and resting to assist in combating the effects of driver fatigue. Other research, such as Brice & Smith (2002) and Reyner & Horne (2002) should be used in conjunction with this study to obtain a comprehensive picture of the effects of caffeine and glucose on driver performance.