Effects of Intensity of Short-Wavelength Light on the EEG and Performance of Astronauts During Target Tracking

Abstract

In complex human-machine systems such as spacecraft, poor astronaut performance leads to dangerous accidents, and assessing the functional state of astronauts during a mission has positive impacts on risk reduction and efficiency. This paper aimed to assess the functional state of astronauts in performing target tracking tasks of different difficulty at three different short-wavelength light intensities (40 lx, 80 lx, and 160 lx) in a simulated space station module with a head-mounted display (HMD) and electroencephalogram (EEG) equipment, and collect EEG and task performance changes as well, aiming to better understand the cognitive behavior of astronauts during spacecraft operations. Thirty healthy participants were recruited for this experiment and their EEG physiological signals were collected during simulated astronauts in conducting target tracking tasks. Meanwhile, all participants wore a head-mounted display (HMD) to perform target tracking tasks of low, medium, and high difficulty in three intensities (40 lx, 80 lx, and 160 lx) of short-wavelength light ($\lambda_{max}$ = 475 nm), while remaining in the darkness (<1 lx). All the participants’ EEG power in the beta range after exposure to 160 lx light was significantly higher than that to 40 lx and 80 lx light, or it kept in the darkness. In addition, alpha and theta power were significantly lower in 160 lx light than in darkness. This study provides some evidence that nighttime short-wavelength light exposure can improve the astronaut task performance in performing target tracking.