Differential Effects of Modafinil on Performance of Fatigue Susceptible and Fatigue Resistant Individuals

Sleep deprivation uniquely affects individuals, with some displaying more resistant tendencies than others, demonstrating the need for countermeasures for fatigue-vulnerable individuals. The present study examined whether 200mg modafinil affects the performance of fatigue-vulnerable differently than fatigue-resistant individuals. Using a 3-way, placebo-controlled, mixed-model design, 22 individuals completed various cognitive tasks and self-report questionnaires over 36 hours of continuous wakefulness. Results demonstrated that performance of fatigue-vulnerable individuals was significantly improved by modafinil administration fatigue-resistant individuals did not receive a similar boost. The improvements were task dependent, with some tasks showing marked effects while others showing little to no effects. Subjective assessments demonstrated that modafinil did not affect fatigue-vulnerable individuals differently from fatigue-resistant individuals. Pursuing differentiation of those who benefit most from modafinil allows for more precise resource allocation by tailoring fatigue-countermeasures by need. Improvements in performance for fatigue-vulnerable individuals equates to fewer errors in tactical settings and improved wartime outcomes.