Effects of modafinil and sleep loss on physiological parameters

Objective: The purpose of this study was to determine the effects of modafinil administration on physical performance, thermoregulation, and total energy expenditure (TEE) during continued wakefulness in Air Force operators. Methods: Participants (N = 12) were randomly assigned to the modafinil or placebo group. Participants performed physical performance and testing during 72 hours of wakefulness. Results: There were no differences between groups for physical performance. Oral temperature was higher for modafinil compared to placebo (36.5 ± 0.2°C versus 36.3 ± 0.2°C for modafinil and placebo, respectively, p < 0.05). Daily water turnover (8.8 ± 1.0 L·day^-1 and 9.0 ± 1.5 L·day^-1) and total energy expenditure (19.4 ± 3.7 and 19.9 ± 2.1 MJ) were similar between the modafinil and placebo groups, respectively. Conclusion: modafinil did not improve physical performance. Despite elevating oral temperature, water turnover and TEE were similar between treatments. These findings suggest it is unnecessary for operators taking modafinil to carry additional fluids and/or food.