Hypothesis: Caffeinated energy drinks can improve driving simulator performance in sleep deprived residents
Methods: 26 anesthesiology residents were randomized to two groups after their 6th consecutive overnight shift. One group consumed caffeine prior to using a driving simulator at the end of their final night float shift, while the other group did the same with no caffeine. These groups then switched to the opposite intervention arm after a subsequent week of night float, ie they crossed over.
Results: Primary outcome included lateral lane deviations, lane crossings, collisions and off-course driving during the simulator test. Residents in the caffeine cohort had fewer lane deviations and struck fewer obstacles in the final third of the simulated drive.
Strengths:
Relevant question
Randomized, single blinded
Crossover analysis allows residents to serve as their own controls
High fidelity simulator eliminates subjectivity and emphasizes objective measures of driving performance
Internally valid
Weaknesses:
Small sample size
Weak external validity
Study groups matched for everything except baseline caffeine consumption
Key Point: Caffeine may improve driving safety during states of relative sleep disruption