The Effect of Caffeine and Sleep Quality on Military Pilot Students’ Flight Performance-Related Cognitive Function

ABSTRACT Objective To assess the effect of caffeine and sleep quality on the flight performance-related cognitive function. Background High levels of cognitive performance in pilots is required for flight safety. Methods Students at a military flight school in Thailand were invited to participate in this study. Exclusion criteria was positive screening for caffeine use disorder. We examined three cognitive functions required for flight performance: (1) vigilance (Mackworth Clock Test), (2) situational awareness, including memory (Corsi block-tapping test) and spatial reasoning (mental rotation test), and (3) reaction time (Deary-Liewald task). Neuropsychological tasks were performed before and 30 minutes after drinking a bottle of 220 ml coffee containing 143 mg of caffeine. Sleep quality was measured by the Thai-Pittsburgh Sleep Quality Index. Results Twenty-nine healthy males without caffeine use disorder with a mean age of 25.1 years were enrolled. After low-dose caffeine intake (<3 mg/kg body weight), cognitive performance improved significantly in vigilance, situation awareness, and reaction time. Baseline cognitive performance was not different between high (HSQ) and low sleep quality (LSQ) groups. After drinking coffee, however, participants with HSQ demonstrated improvements in vigilance and reaction time, while the LSQ group had improved vigilance only. Conclusion Low dose caffeine improved vigilance, situational awareness, and reaction time which were cognitive functions required for flight performance. The cognitive-enhancing effect of caffeine was more obvious in student pilots with high-quality sleep.