Fatigue and management of warfighter mental endurance.

Mental fatigue (MF) is a psychobiological state induced by prolonged exertion that has the potential to reduce performance. In military operations, MF coincides with inadequate sleep, circadian disruption and other stressors, further increasing the risk of fatigue-related errors of judgement and reduction in physical and psychological performance. Experienced leaders can detect MF, but multimodal monitoring and assessment technologies still cannot duplicate this capability. Experiments to define signals that cue this human percept could inform future technologies. Countermeasures include engagement strategies, brain endurance training to extend physical endurance, and caffeine and modafinil to temporarily sustain performance. An infrastructure for physiological monitoring and integrated analyses will advance team performance enhancement, along with the use of explainable and interpretable artificial intelligence modelling, refined through iterative experimentation. More precise definitions that distinguish MF from other types of fatigue will help advance the development of monitoring technologies and countermeasures by targeting the right physiological and behavioural metrics.