Modeling and Entraining Human Capability in Space

Space operations are extraordinarily challenging endeavours, demanding high cognitive performance and alertness from both astronauts and ground-based crew. Due to the nature of the space environment and mission constraints, it can be difficult to entrain, or align, the body’s internal ~24.2-h circadian rhythm to the required day length (e.g., the 24-h Earth day or the 24.65-h Mars day), to adapt to shifts in sleep/wake or work schedules, and to obtain sufficient sleep. Both circadian rhythms and sleep physiology significantly affect human performance, alertness, mood, and other physiology. To address these concerns, mathematical models of human circadian rhythms, sleep, performance, and alertness have been developed. These models can be used to predict how individuals will function on different schedules, to suggest strategies to improve performance, to entrain circadian rhythms, and to optimize the use of countermeasures such as light, naps, and pharmaceuticals. These models are also applicable to other settings where individuals face difficulties entraining or shifting their circadian rhythms, such as shift-work, or where performance failures present a high risk, such as aviation, healthcare, security, and transportation.