Sensitivity of S-Cat to Sleep Deprivation

Abstract : NASA has need of a rapid, reliable and non-invasive means to objectively evaluate the cognitive ability of astronauts to perform mission critical tasks, particularly during extended duration space flight One such means under consideration is the Spaceflight-Cognitive Assessment Tool (S-CAT), a tool designed to assess cognitive performance using a set of five cognitive performance tests. The current study had multiple goals, one of which was to evaluate the sensitivity of S-CAT to fatigue induced by sleep deprivation and circadian disruption. Research Hypothesis. Since S-CAT has demonstrated sensitivity to organic neural dysfunction, it was expected to show fatigue sensitivity. Methods. Two groups of eight US military pilots (ages 30-40) were deprived of sleep for 46 hrs, over two circadian performance nadirs. In addition to S-CAT, four other cognitive performance tests were performed repeatedly during the sleep deprivation period. The S-CAT battery of tasks was performed once every six hours up to the 33rd hour while the participants were in the experimental situation. Results. For all tests, the response time measures showed the greatest effects from fatigue. Two of the five S-CAT tests, the Matching to Sample and the Math tests, exhibited significant fatigue-related decrements on response time. The Matching to Sample test and the Continuous Processing test showed effects on accuracy and percent correct For Continuous Processing, 4 of 6 trials were affected, beginning after 23 hrs of wakefulness and lasting until 35 hours awake. Pilots appear to be somewhat less vulnerable to fatigue compared with data from other sleep deprivation experiments. Conclusion. It is likely that S-CAT will identify astronauts too fatigued to optimally perform sensitive missions.