Doan BK, Hickey PA, Lieberman HR, Fischer JR. Caffeinated tube food effect on pilot performance during a 9-hour, simulated nighttime U-2 mission. Aviat Space Environ Med 2006; 77:1034–1040.
Introduction: Interventions to maintain performance are necessary to meet demanding mission requirements during sustained and surge aviation operations. Tube foods are the only foods that can be consumed during a U-2 mission due to the confining and encapsulating nature of required support equipment. Caffeine is a safe and effective strategy to enhance cognitive performance and is an ingredient in some tube foods. The objective of this study was to determine whether moderate doses of caffeinated tube foods would enhance performance in a simulated U-2 mission. Methods: Volunteers were 12 healthy USAF male pilots. The study used a double blind, placebo-controlled, two-factor, repeated-measures (five iterations per night) design. Caffeinated (200 mg each) or placebo tube food was consumed at 00:00 and 04:00. Dependent measures assessed included standardized tests of cognitive performance, vigilance, and mood designed to simulate the demands of a nighttime U-2 mission. Results: Statistically significant (p < 0.05) improvements in performance due to caffeine administration compared with placebo were present in all five cognitive tasks either as main effects, interactions, or absence of significant degradation in the caffeine treatment condition compared with the placebo condition. A majority of sleep deprivation-induced performance decrements were attenuated by 200 mg of caffeine in tube food consumed every 4 h, and in some cases, performance was improved beyond baseline levels. Conclusions: Caffeinated tube food maintained cognitive performance representative of U-2 long-duration mission tasks at or near baseline levels for a 9-h overnight period in qualified USAF pilots. Side effects were minor and did not differ between placebo and caffeine conditions.
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